The United States is poised to launch a military strike on Syria in coming days after determining that President Bashar al-Assad's regime used chemical weapons during an attack outside Damascus last week which killed hundreds of civilians.
Several lawmakers sought to put the brakes on what Republican congressman Scott Rigell, who drafted the letter to Obama, said could be potential abuse of presidential authority if he decides to attack Syria without a congressional green light.
Congress is on recess until September 9, but "members can reconvene at your request," Rigell wrote in his letter, which as of late Tuesday had 40 rank-and-file co-signers including six Democrats.
While decrying the use of chemical weapons as "beyond the pale," House Foreign Affairs Committee chairman Ed Royce warned that US intervention could trigger an "escalation" of the Syria crisis.
The Obama "administration should come to Congress to explain their plans," Royce said.
"The consequences are too great for Congress to be brushed aside."
US Vice President Joe Biden said Tuesday that there was no doubt the Syrian regime had used chemical weapons against civilians and said those who had done so must be held accountable.
"The president believes and I believe that those who use chemical weapons against defenseless men, women and children should and must be held accountable," Biden told US veterans in Houston.
US national security is strengthened "when we hold accountable those who violate international norms that are the foundation of global security, and ultimately, American security," he said in laying out the case for action in Syria.
Biden stressed that in Syria the regime was the only one with chemical weapons and the means to use them.
The United States said Tuesday it will release intelligence on the alleged chemical weapons attack in Syria, which reportedly killed hundreds of civilians, later this week. Meanwhile US President Barack Obama and Canadian Prime Minister Stephen Harper agreed that the use of chemical weapons in Syria merited a firm, effective and timely response from the international community.
"I think you can expect it this week," White House spokesman Jay Carney told reporters at a daily briefing, amid widespread expectations that the United States would launch a military response to the alleged use of chemical agents.
Carney reiterated that Obama had not made a decision on how the United States will respond to what it believes was an attack on civilians by the Syrian government.
"When the president has an announcement to make, he'll make it," Carney said.
The White House spokesman also said Tuesday there should be "no doubt" that the Syrian government launched last week's devastating chemical weapons attack, believed to have killed hundreds of civilians.
Jay Carney said there "should be no doubt, for anyone who approaches this logically, that the Syrian regime is responsible for the use of chemical weapons on August 21 outside Damascus."
Earlier on Tuesday US President Barack Obama and Canadian Prime Minister Stephen Harper agreed that the use of chemical weapons in Syria merited a firm, effective and timely response from the international community, a spokesman for Harper said.
The two leaders talked amid mounting signs that Washington and its allies are edging toward a limited use of force against Syrian President Bashar al-Assad's loyalists in the wake of a poison gas attack last week that killed hundreds of civilians.
"Both leaders agreed that significant use of chemical weapons merits a firm response from the international community in an effective and timely manner," Harper spokesman Andrew MacDougall said in a statement.
Update: Syria's opposition expects a Western military intervention against President Bashar al-Assad's regime within days and has been consulted over targets, one of its officials said Tuesday.
"There is no precise timing ... but one can speak of an imminent international intervention against the regime. It's a question of days and not weeks," said Ahmad Ramadan, a Syrian National Coalition political committee member.
"There have been meetings between the Coalition, the (rebel) Free Syrian Army and allied countries during which possible targets have been discussed," the official said.
Ramadan said they included airports, military bases and arms depots.
The targets cover "airports used by planes equipped with missiles and explosive barrels, command centres used by regime officers, (Iranian) Revolutionary Guards and by (Lebanese Shiite militant group) Hezbollah," he said.
Ramadan also said bases used to fire missiles and Scuds, especially the army's Brigade 155 near Damascus, were targets for Western punitive strikes following alleged chemical weapons attacks last week.
Meanwhile National Coalition's envoy in Paris also said they have been informed of a possible military strike on Syria.
"We have been informed of a strike by the world powers to punish the Syrian regime but we do not have the details," Monzer Makhous, the National Coalition's envoy in Paris, said.
"This is being left for the world powers to decide."
He adds: "We will support any move to punish such a regime, which has been killing its own people to remain in power at any expense."
American missile strikes against Syria could come "as early as Thursday," said senior US official, reported NBC News.
The "three days" of strikes would be limited in scope, and aimed at sending a message to the regime of Syria President Bashar Assad, US officials said.
It followed another round of telephone diplomacy by President Barack Obama, who held discussions with Australian Prime Minister Kevin Rudd and French President Francois Hollande as well as on Monday to lay the groundwork for potential military action.
Western countries have received the list of targets for air strikes in Syria from the Syrian opposition, reported sources.
The West is also urging the opposition to get ready for participation in Geneva-2 peace conference despite the planned air strikes.
Western powers told the Syrian opposition to expect a strike against President Bashar al-Assad's forces within days, according to sources who attended a meeting between envoys and the Syrian National Coalition in Istanbul.
"The opposition was told in clear terms that action to deter further use of chemical weapons by the Assad regime could come as early as in the next few days, and that they should still prepare for peace talks at Geneva," said one of the sources who was at the meeting.
US military ready to act on Syria immediately, West to strike soon
The US military is ready to act immediately should President Barack Obama order action against Syria over a chemical weapons attack, Defense Secretary Chuck Hagel said in a television interview with the BBC on Tuesday.
"We have moved assets in place to be able to fulfill and comply with whatever option the president wishes to take," Hagel said during a trip to Brunei, according to the BBC.
Asked if the US military was ready to respond just "like that," Hagel said: "We are ready to go, like that."
The US Department of Defence had provided President Obama with "all options for all contingencies," Hagel said.
He added that intelligence currently being gathered by the UN inspectors would confirm that the Syrian government was responsible for the chemical attacks in last week.
"I think the intelligence will conclude that it wasn't the rebels who used it, and there'll probably be pretty good intelligence to show is that the Syria government was responsible. But we'll wait and determine what the facts and the intelligence bear out," US Defense Secretary said.
Meanwhile Syrian Foreign Minister Walid Moallem said he rejected "utterly and completely" claims that Syrian forces had used chemical weapons.
His government has blamed rebel fighters for the suspected chemical attack, which took place on 21 August near the Syrian capital Damascus, and reportedly killed more than 300 people.
A possible Western intervention in Syria would not bring an "easy victory" because the Damascus government has enough air defence systems to rebuff attacks, the Interfax news agency said Tuesday.
"If the US army together with NATO launch an operation against Syria there won't be an easy victory," the news agency quoted a military-diplomatic source as saying.
"Multi-functional surface-to-air missile system Buk-M2E and other means of air defence that the Syrian troops possess will give a proper response to the aggressors," the source added.
The source said Syria currently has up to 10 batteries of such air defence systems.The Soviet- and Russian-made Buk are medium-range surface-to-air missile systems designed to engage cruise missiles, bombs and unmanned aircraft.
Several Western countries led by the United States are considering air strikes against the Damascus regime in response to an alleged chemical weapons attack by the Syrian troops last week.
Moscow said the use of force against its traditional ally would have "catastrophic consequences" for the region and that Russia would not be militarily involved in the conflict.
Syria will press on with its military efforts despite any potential foreign strikes on its territory, the foreign minister said on Tuesday, adding that any strike would serve the interest of al Qaeda-linked rebel groups.
"The war effort lead by the United States and their allies will serve the interests of Israel and secondly Al-Nusra Front," an Al-Qaeda-linked jihadist group in Syria, Moallem told a press conference in Damascus.
"The (government's) military effort will not stop around Damascus. If the purpose is to limit the victories of our armed forces, they will not be successful," Walid Moallem said.
Any foreign strike on Syria to try to create a balance of power in the war between President Bashar al-Assad's forces and the rebels is "delusional", the foreign minister said on Tuesday.
"If the purpose of a possible (foreign) military strike is to achieve a balance of power ... it's delusional and not at all possible," Walid Moallem added.
"Either we surrender or defend ourselves with the available means - I say this is the better option," Moallem told journalists.
"If they wanted to attack Syria using claims - utterly incorrect claims - about the use of chemical weapons, I defy them to provide what evidence they have," he said.
UN chemical weapons inspectors were delayed in their second visit to alleged chemical weapons sites by disputes among rebel groups, Walid Moallem said earlier.
"Yesterday, they indicated that they wanted to visit a second site, and we said we had no problem. We asked whether they had contacted the other side and they said, 'Of course'", Moallem told a press conference.
"We were surprised today that they did not go there because the gunmen there had not agreed among themselves," Moallem continued.
"I say this to show that the Syrian forces are committed to their engagements and the Syrian side is not obstructing the inspectors."
The actions of the United States and its allies confirm their readiness to carry out a large-scale strike involving cruise missiles on Syria, and it is only a matter of time before they do so, State Duma Foreign Affairs Committee Head Alexei Pushkov told Interfax on Tuesday.
"The conclusion comes from the events of the last few days and the official statements of the western countries' representatives: the US and its allies have made a choice in favor of a large-scale strike on Syria, and it is just a matter of time now before this strike is carried out," Pushkov said.
The military action appears to have been preordained, the Duma deputy said. "It will consist of a large-scale strike with cruise missiles against military, command and infrastructure facilities in Syria from four US battle ships and a British Trafalgar submarine equipped with Tomahawk missiles," Pushkov said.
Russia on Tuesday warned a military intervention in Syria could have "catastrophic consequences" for the region and called on the international community to show "prudence" over the crisis.
"Attempts to bypass the Security Council, once again to create artificial groundless excuses for a military intervention in the region are fraught with new suffering in Syria and catastrophic consequences for other countries of the Middle East and North Africa," the foreign ministry said.
"We are urging our American colleagues and the entire international community to yield to reason and act in strict compliance with international law and the founding principles of the UN Charter,” the diplomat said.
"A more urgent task is to call the Geneva-2 [conference on Syria], and we hope that the US will fulfill its part of the deal concerning preparations for this conference," he said.
It was announced earlier that a Russian-US working meeting, which was supposed to take place in the Hague on August 28 and address preparations for the proposed international conference on Syria, was postponed at Washington's initiative.
Russia has no evidence of whether a chemical weapons attack has taken place in Syria or who is responsible, Russian President Vladimir Putin told British Prime Minister David Cameron in a telephone call, according to Cameron’s official website.
The two leaders had an urgent phone call on Monday afternoon regarding the Syrian crisis in the wake of a sniper attack on UN chemical inspectors outside Damascus.
Following the call the British government spokesperson said: "President Putin said that they did not have evidence of whether a chemical weapons attack had taken place or who was responsible."
Both national leaders reaffirmed the stance that all G8 attendees took in June: "No-one should use chemical weapons and any use would merit a serious response from the international community."
Following last week’s chemical attack, the West has engineered a media campaign to facilitate a military incursion, says Russia’s Foreign Minister Sergey Lavrov. He also cast doubts on the veracity of US and European claims about the incident.
"Officially Washington, London and Paris say they have incontrovertible evidence that the Syrian government is behind the chemical attack in Damascus, but they have not presented this evidence. Yet, they keep saying that the ‘red line’ has been crossed,” Lavrov said during an emergency press conference in Moscow.
"Now, we are hearing calls for a military campaign against Bashar Assad”.
Last Wednesday, footage began to emerge of civilians in a Damascus suburb suffering from what appeared to be the effects of a neurotoxic gas.
Medical aid group, Doctors without Borders, have reported that at least 355 people died as a result of the incident.
The Syrian opposition, which has been involved in the 30-month conflict with the government of Bashar Assad, said state forces had been behind the release. The Syrian government has denied the claims, saying that the use of chemical weapons after repeated warnings from the international community would be "illogical”.
In his conference, Lavrov questioned the rebel version of events.
"There is information that videos were posted on the internet hours before the purported attack, and other reasons to doubt the rebel narrative.”
"Those involved in the incident wanted to sabotage the coming Geneva peace talks. Maybe that was the motivation for those who created this story. The opposition obviously does not want to negotiate peacefully”.
Read the full transcript of FM Lavrov's emergency press conference on Syria here.