The call for a quick international strike against Syria faced a major pushback Thursday, when British lawmakers in the House of Commons voted 285-272 against the motion proposed by Prime Minister David Cameron.
Unlike the military offensive against Libya in 2011 which was carried out by a large coalition, officials said US President Barack Obama is prepared to act in coming days without Britain.
"Here, what's being contemplated is of such a limited and narrow nature that it's not as if there's a similar imperative for bringing in different capabilities from different countries," a senior administration official said, the Wall Street Journal reported on Thursday.
"We believe it's important that there be diplomatic support from key allies, and we think we're getting that."
While, intelligence officials have indicated that the US has “no smoking gun” proving Syrian President Bashar al-Assad ordered the use of chemical weapons on militant strongholds last week, the White House says it is convinced Damascus was responsible for the attack.
A report by the Office of the Director for National Intelligence has also concluded that it does not have proof President Assad ordered the chemical attack, US intelligence officials said.
Before the vote in British Parliament, White House spokesman Josh Earnest suggested that Washington was willing to go solo on Syria.
"When the president reaches a determination about the appropriate response ... and a legal justification is required to substantiate or to back up that decision, we'll produce one on our own," Earnest said.
Also on Thursday, President Obama spoke with German Chancellor Angela Merkel, who said the issue of chemical attack in Syria should be addressed by the United Nations Security Council, signaling Germany's hesitation to back a US request for military action.
The US has beefed up its military presence in the eastern Mediterranean. According to media reports, four US warships and a submarine are in the region and a fifth is on the way. All destroyers are cruise-missile equipped.