(Updates throughout)

U.S. President Barack Obama said Saturday he had decided on "military action" against Syria but would seek congressional approval first.

"After careful deliberation, I have decided that the United States should take military action against Syrian regime targets," Obama, accompanied by Vice President Joe Biden, said in the White House Rose Garden.

Obama, whose administration accuses President Bashar al-Assad's government of using chemical weapons in an Aug. 21 massacre in the rebel-controlled Ghouta area outside Damascus, said the attack was an "assault on human dignity" and represents a "serious danger to our national security."

He gave no specific date for the strike, saying it would occur when Washington decides.

The president said he would "seek authorization for the use of force from the American people's representatives in Congress," but did not indicate how he would respond if lawmakers reject the plans for military action.

Congress is currently on summer recess, but is scheduled to return to session on Sept. 9.

"We cannot raise our children in a world where we do not follow through on things we say," Obama said, referring to his earlier threat that the use of chemical weapons by Damascus would cross a "red line" and provoke a U.S. military response.

Reiterating comments made Friday, Obama said the military action would be "limited in duration and scope" and not involve "boots on the ground" or an "open-ended intervention."

The U.S. government released a report Friday stating that a chemical weapons attack was carried out on Aug. 21 in Ghouta that killed 1,429 people, including 426 children.

Secretary of State John Kerry said U.S. intelligence had concluded with "high confidence" that Assad's government was "witting of and directed the attack."

Calling the U.S. accusations "an insult to common sense," Assad has said it would have been illogical to order a chemical attack with U.N. weapons inspectors already in the country and government forces holding the upper hand in the armed conflict.

He says rebels may have carried out the attack in a bid to provoke foreign intervention in the conflict.

U.N. inspectors in Syria to investigate the Aug. 21 incident and other alleged chemical weapons attacks left the country Saturday.

The inspectors on Friday wrapped up their fourth day of site visits and evidence gathering related to the alleged use of chemical weapons in Ghouta, Martin Nesirky, spokesman for U.N. Secretary-General Ban Ki-moon, said at press briefing Friday.

He said the inspectors would issue a report once the samples they gathered have been fully analyzed.

"The investigation, as with the investigation into the other allegations (of chemical weapons attacks in Syria), is, as we have repeatedly said, to establish whether chemical weapons were used, not by whom," Nesirky said.

Britain's House of Commons voted 285-272 this week against a motion that would have opened the door to that country's participation in a U.S.-led strike, but France said it remained "prepared" to participate in a punitive action against Syria.

More than 92,000 people died in Syria's internal conflict between March 2011 and April 2013, according to a report released in June by the U.N. Office of the High Commissioner for Human Rights. EFE