President Obama has concluded that Syria used chemical weapons, he tells PBS NewsHour. Obama, however, said he has not made a decision about a possible military strike.

The president said it's clear that chemical weapons were used, and he said the US has ruled out the possibility that the rebels were responsible, as Bashar al-Assad's government claims.

"We have concluded that the Syrian government, in fact, carried these out, and if that's so, then there need to be international consequences."

The US is in consultation with its allies, he said, adding that "I have no interest in any kind of open-ended conflict on Syria." Pressed on what such a limited action would accomplish, Obama said it would send a "pretty strong signal" to the Assad regime that it must stop the chemical attacks.

"You are not only breaking international norms and standards of decency, but you're also creating a situation where US national interests are affected."