The Obama administration said Wednesday that it would go it alone in taking action against Syria as President Obama said the U.S. has “concluded” that the Syrian government carried out a chemical attack last week and Russia stymied efforts to pass a U.N. resolution authorizing military action.

“We have concluded that the Syrian government in fact carried these out,” Obama said in his lengthiest comments yet about the chemical attack during an interview with PBS’ “Newshour.” “And if that’s so, then there needs to be international consequences.”

Even though Britain was one of the most aggressive U.S. allies in calling for a military response to the attack, it complicated the timing of a response Wednesday by submitting a draft resolution to the U.N. Security Council that would have authorized the use of military force against Syria.

As expected, Russia objected to military intervention and prevented the five-member security council from approving the resolution. Russia and China have blocked previous attempts to sanction the Assad government and even prevented the U.N. from releasing a statement condemning the use of chemical weapons without placing blame on Assad’s forces.

Britain signaled late Wednesday that it would wait for a U.N. investigation into the use of chemical weapons near Damascus before holding a parliamentary vote on the use of force in Syria, a prospect that pushes a military strike further down the road.

A State Department spokeswoman said the U.S. would not be delayed by U.N. inaction.

“We cannot be held up in responding by Russia’s continued intransigence at the United Nations … the situation is so serious that it demands a response,” Marie Harf told reporters.

Obama told PBS that he was trying to avoid getting the U.S. into an open-ended conflict in Syria, and stressed that any U.S. response would be limited. He said Syria’s deadly chemical attack violated international norms and threatened “America’s core self-interest.”

“We do have to make sure that when countries break international norms on weapons like chemical weapons that could threaten us, that they are held accountable,” he said.

Despite strong words from Obama and administration officials, any military strike, which was expected as soon as Thursday, could be delayed. White House officials earlier this week said they planned to make a report by the intelligence community providing proof that Assad’s government used chemical weapons on its own people public before taking military action. Even so, the administration has yet to disclose the assessment amid reports that some in the intelligence community want more evidence that Assad himself ordered the attack.

U.S. intelligence agencies intercepted a Syrian military commander’s communications expressing surprise over the attack, leading some to conclude that Assad himself may not have ordered the attacks, Foreign Policy’s The Cable news blog reported early Wednesday.

The White House now reportedly wants more proof directly linking Assad or someone in his inner circle to the attacks.

In another sign that the attacks aren’t imminent, the administration is planning a Thursday teleconference briefing on Syria for leaders of the House and Senate and national security committees in both parties.