President Obama said Wednesday that the military strike on Syria he is contemplating was for the limited purpose of preventing the further use chemical weapons, and was not intended to insert the US into the bloody Syrian civil war. Even as he said he had not made a final decision, Obama's precise explanation of the scope and purpose of prospective US military action made clear that he has all but made up his mind.

"If we are saying in a clear and decisive but very limited way, we send a shot across the bow saying, 'Stop doing this,' this can have a positive impact on our national security over the long term," Obama told PBS’s News Hour Wednesday.

The President’s comments came as the United Kingdom, facing demands from opposition lawmakers, signaled it wouldn’t be prepared to participate in any action for another week, following two votes by parliament and consideration of a UN inspectors' report on Syria.

US officials said while they were closely consulting with their British allies, they weren’t going to wait for the UN report to act. UN inspectors were expected to leave the country by the weekend, but do not have a mandate to determine accountability for any chemical weapons evidence they were able to obtain. US Secretary of State John Kerry said Monday the Syrian regime knowingly delayed UN inspectors’ access to the site of the alleged August 21 chemical weapons attack for five days, and deliberately destroyed evidence by continuing to shell the area, in the Ghouta region outside Damascus.