US Defence Secretary Chuck Hagel said Britain has strongly and publicly condemned Syria's alleged gas attacks, adding, "That vote in the Parliament doesn't change that."
Mr Hagel told a news conference this morning, "Every nation has a responsibility to make their own decisions, and we respect that of any nation ... We'll continue to work with Britain and consult with Britain as we are with all our allies."
Mr Hagel stressed that the Obama administration wants "an international collaboration and effort" whatever decision is taken.
The US will keep talking to the UK and other countries on "ways forward together," he added.
US Defence Secretary Chuck Hagel has expressed regret to an Indian-born college professor for jokingly asking, "you're not a member of the Taliban, are you?" seconds before the professor rose to ask a question.
Hagel's spokesman said the joke was not directed at anyone in particular, and the defence secretary called the professor, Robin Gandhi, to tell him as much hours after the event at the University of Nebraska, where Hagel gave a speech and took questions from the audience.
Hagel "expressed regret for any trouble that this caused the professor," spokesman George Little told reporters.
"They had a very good discussion and (Hagel) wanted to leave no impression that this joke was directed at anyone in particular, including the professor," Little said.
He added that the defence secretary a little earlier in the programme had answered a question about the Taliban, the Afghan insurgent group.
Gandhi said in a statement that he was honoured to hear Hagel's speech and enjoyed the secretary's answer to his question about cyber weapons.
"Before I rose to ask a question, there was apparently some confusion that did not involve me," Gandhi said, suggesting he too did not believe Hagel's joke was addressed at him.
US Defence Secretary Chuck Hagel said plans to bolster the country's missile defences were in response to "irresponsible and reckless provocations" by North Korea, which threatened a preventative nuclear strike against the US last week.
In addition to the 14 new anti-missile interceptors being added at Fort Greely in Alaska, the Pentagon has also left open the possibility of creating a site on the US East Coast where it could field more interceptors capable of striking down an incoming missile.
Hagel told a news conference, "By taking the steps I outlined today we will strengthen our homeland defence, maintain our commitments to our allies and partners, and make clear to the world that the United States stands firm against aggression".
Last week, North Korea issued a threat to stage a pre-emptive nuclear attack against the US as the United Nations readied new sanctions against Pyongyang in response to its nuclear test on February 12.