A line has been crossed in Syria: Barack Obama

8220;But the use of chemical weapons and the dangers that poses to the international community,to neighbours of Syria,the potential for chemical weapons to get into the hands of terrorists 8212; all of those things add increased urgency to what is already a significant security problem and humanitarian problem in the region,8221; Obama said in response to a question.

Syria was one of the major topics of discussion between the two leaders in the Oval Office of the White House.

A day earlier,the White House said it has been assessed by the intelligence community,with varying degrees of confidence,that the Assad regime has used chemical weapons on a small scale in Syria,specifically the chemical agent sarin.

This assessment is based in part on physiological samples,it said.

8220;What we have right now is an intelligence assessment. And as I said,knowing that potentially chemical weapons have been used inside of Syria doesn8217;t tell us when they were used,how they were used,8221; Obama said.

8220;Obtaining confirmation and strong evidence,all of those things we have to make sure that we work on with the international community. And we ourselves are going to be putting a lot of resources into focusing on this,8221; he said.

Obama said the United States is going to be working with countries like Jordan to try to obtain more direct evidence and confirmation of this potential use.

8220;In the meantime,I8217;ve been very clear publicly,but also privately,that for the Syrian government to utilise chemical weapons on its people crosses a line that will change my calculus and how the United States approaches these issues,8221; he said.