President Barack Obama strongly suggested Tuesday he'd consider military action against Syria if it can be confirmed that President Bashar Assad's government used chemical weapons in the two-year-old civil war.

At a White House news conference, the president also defended the FBI's work in monitoring the activities in recent years of one of the men accused in the deadly bombing at the Boston Marathon two weeks ago.

At a question and answer session that ranged from immigration legislation to recent intelligence cooperation with Russia, the president several times chided, criticized or dismissed his Republican critics. Asked about one senator who recently said national security protections have deteriorated since he became president, Obama said, Sen. Lindsey "Graham is not right on this issue, although I'm sure he generated some headlines."

Asked about Syria, the president said that while there is evidence that chemical weapons were used inside the country, "we don't know when they were used, how they were used. We don't know who used them. We don't have a chain of custody that establishes" exactly what happened.

Read it at Associated Press.