With just two hours notice, President Obama announced a press conference to begin at 10:15 this morning, to cover unspecified topics. The President did not read any prepared remarks, but opened the floor up immediately for questions.

As many news sources predicted, Syria was at the top of the list. Last Thursday, Secretary of Defense Chuck Hagel stated that U.S. intelligence was reporting, with varying degrees of certainty, that chemical weapons had been used in Syria. Since then, the world has been waiting uneasily for an update, so it was no surprise that this was the first question the President took.

Ed Henry of Fox asked the President if, given his previous statement on Assad’s use of chemical weapons as a game changer, he risks credibility by not taking military action against the Syrian regime.

Obama answered by confirming that chemical weapons have indeed been used in Syria – suggested that U.N. analysis has come back positive – but qualified this confirmation by adding, ” we don’t know how they were used, when they were used, who used them [and] we don’t have chain of custody that establishes what exactly happened”.

He went on to say that – to ensure  international support – he refuses to act without “hard, effective evidence”, but that his administration is “deeply engaged” on the question of best possible action on Syria.

Following up on his remarks Friday, Obama was asked if his use of the phrase “game changer” referred to military intervention, specifically. He did not go into detail, but acknowledged that he has had the Pentagon looking at military options since last year and that the threat Assad’s chemical weapons pose to the U.S. and its allies in the Middle East might certainly warrant such a reaction.

His statements today will likely be taken as wise caution by some, and more tiptoeing by others. One interesting phrase, which will likely receive less attention than it deserves, is “chain of custody”. Last week, these words were used to describe the path of chemical samples from Syria to U.S. and U.N. analysts, but in the context above it seems the president may be referring to the path of the chemical weapons themselves, from storage to use, posing the questions of whether or not Assad is still in complete control of – and communication with – his field commanders.

The full text of the press conference, which also touched on the Boston bombing, Guantanamo Bay, and immigration policy, can be found here.