WASHINGTON (AP) — President Barack Obama says he hasn't made a final decision about a military strike against Syria. But he says he's considering a limited and narrow action in response to a chemical weapons attack that he says Syria's government carried out last week.

Obama says that attack was a challenge to the world and threatens U.S. national security.

Obama's comment came after the U.S. released an intelligence assessment that found with "high confidence" that Syrian President Bashar Assad's government carried out a chemical weapons attack last week.

The U.S. says the attack killed more than 1,400 people.

Obama spoke before meeting at the White House with three Baltic leaders.