Obama: Syrian government responsible for chemical weapon attack

Barack Obama said tonight the US had concluded that the Syrian government carried out a large-scale chemical weapons attack against civilians.

President Obama said the US had examined evidence and did not believe the opposition fighting the Syrian government possessed chemical weapons or the means to deliver them.

Mr Obama says he has not made a decision about how America will respond.

The White House says it is planning a possible military response while seeking support from international partners.

But the US has not yet presented concrete proof of Syrian government involvement in the attack.

Some lawmakers are calling for Mr Obama to seek congressional approval for military action following the chemical attack last week.

Mr Obama did not present any direct evidence to back up his assertions. He said he was still evaluating options for possible military retaliation, but vowed that any American response would send a "strong signal" to Syrian president Bashar Assad.

In a PBS interview Mr Obama said the US had concluded that the Syrian government carried out the chemical weapons attack and "there need to be international consequences".

The president says he is not seeking a lengthy, open-ended conflict in Syria, indicating that any US response would be limited in scope.

Meanwhile the US Navy is beefing up its presence in the Persian Gulf region, increasing the number of aircraft carriers from one to two.

The USS Truman has arrived in the Arabian Sea and was due to take the place of the USS Nimitz, which was supposed to head home. The navy has ordered the Nimitz, which is in the Indian Ocean, to stay for now.

US officials describe the decision as prudent planning and say it does not suggest the carrier would play a role in any possible strikes in Syria.

The US had kept two carriers in the region, but budget cuts in February forced officials to cut that to one.