Russia’s Putin warns US against ‘aggression’ in Syria without UN approval

Kerry pleads his case for Syrian strike to divided Congress 3:40

Russian President Vladimir Putin warned the United States and its allies against unilateral action against Syria on Wednesday – but said he “doesn’t exclude” backing a U.N. resolution if evidence proved the use of poison gas against civilians.

As the White House stepped up its efforts to secure political approval for retaliatory strikes on the regime of Bashar Assad, Putin said acting without the approval of the U.N. Security Council “can only be interpreted as an aggression."

In an interview with The Associated Press ahead of President Barack Obama's arrival in Europe for meetings with G20 leaders, Putin said video footage of the suspected Aug. 21 chemical weapons attack outside of Damascus could have been fabricated by groups "connected with al Qaeda."

Syrian refugees look to America for help 2:50

Asked if Russia might agree to military action if Damascus were proven to have carried out a chemical weapons attack, he answered: "I do not rule it out."

However, he said: "In line with international law, only the U.N. Security Council could sanction the use of force against a sovereign state. Any other pretext or method which might be used to justify the use of force against an independent sovereign state are inadmissible and can only be interpreted as an aggression."

Obama restated his call for an international response on Syria Wednesday, saying the world “cannot be silent” in the face of the “barbarism” should by the Assad regime.

“I didn’t set a red line – the world set a red line,” he told reporters at a news conference in Sweden, where he was on a visit ahead of Thursday’s G20 summit of world leaders in St Petersburg, Russia.

Any failure to respond to the suspected Aug. 21 poison gas attack near Damascus would increase the risk of further attacks, Obama said. There was no dispute that chemical weapons had been used, he said, adding: “The only question is ‘who used them?’”

Putin appeared sanguine when asked about relations with the U.S., opening the door for diplomatic progress after tensions over issues including the fate of NSA leaker Edward Snowden.

"President Obama hasn't been elected by the American people in order to be pleasant to Russia,” Putin said. “And your humble servant hasn't been elected by the people of Russia to be pleasant to someone either. We work, we argue about some issues. We are human. Sometimes one of us gets vexed. But I would like to repeat once again that global mutual interests form a good basis for finding a joint solution to our problems."

Putin spoke as lawmakers in France prepared to debate whether to join U.S.-led military action. Although President Francoise Hollande does not require parliamentary approval for French action, he has echoed British Prime Minister David Cameron in ensuring there is broad support.

Cameron said Wednesday he believed the Syrian government would use chemical weapons against its own people again if allies stepped back from taking military action against it.

Asked by an opposition Labour party lawmaker whether he would push for a ceasefire in Syria rather than a “bombing raid,” Cameron told parliament that Obama had been clear.

“I would just ask her to put herself for a moment in the shoes of the president of the United States,'' Cameron told the lawmaker during his weekly question and answer session in parliament.

“He set a very clear red line, that if there was large-scale chemical weapons use something had to happen. To ask the president of the United States, having set that red line, having made that warning, to step away from it I think that would be a very perilous suggestion to make because in response I think you would see more chemical weapons attacks from the regime.''

However, Cameron reaffirmed Britain's position that it would take no part in any military action within Syria. “I accept that Britain can't be part, and won't be part, of any military action on that front," he told parliament.

The White House on Tuesday won backing from key political figures including members of the Senate Foreign Relations Committee who said it had reached agreement on a draft authorization for the use of military force in Syria – although with narrow terms.

The draft, which could go to a vote as early as Wednesday, would limit military action to 60 days - with a possible 30-day extension – and also barred the involvement of boots on the ground.

“Together we have pursued a course of action that gives the President the authority he needs to deploy force in response to the Assad regime's criminal use of chemical weapons against the Syrian people, while assuring that the authorization is narrow and focused, limited in time, and assures that the Armed Forces of the United States will not be deployed for combat operations in Syria,” Democratic Sen. Robert Menendez, chairman of the Senate Foreign Relations Committee, said in a statement. 

Confronting skeptics of an attack on Syria, Secretary of State John Kerry said Tuesday that the world is watching and wants to know whether the United States will “rise to this moment and make a difference.”

"The president is not asking you to go to war," Kerry said in response to a question asked by Sen. Rand Paul, R-Ky. "He’s simply saying we need to take an action that can degrade the capacity of a man who’s willing to kill his own people by breaking a nearly 100-year-old prohibition, and will we stand up and be counted to say we won’t do that."

NBC News' Erin McClam and Reuters contributed to this report.