US secretary of state John Kerry warned for the first time on Saturday that chances for a political settlement in Syria could be undermined by the Assad regime's use of chemical weapons.
Kerry spoke by phone Friday with his Iraqi counterpart Hoshyar Zebari and the pair discussed Syria and talks set to be held on the crisis in Geneva, the state department said.
The top US diplomat "reaffirmed that the United States continues to work aggressively for a political solution with the goal of a second Geneva meeting," after the first gathering a year ago that set out outlines for a political settlement that was never reached, his office said in a statement.
However, Kerry also stressed that "the use of chemical weapons and increasing involvement of Hezbollah demonstrates the regime's lack of commitment to negotiations and threatens to put a political settlement out of reach," the statement added.
It was the first time the United States sounded so downbeat about prospects for a diplomatic solution to the Syrian crisis. Washington has been planning the peace talks with Russia and the UN since May.
On Thursday, the United States said it had proof that Syrian government forces had carried out deadly chemical weapons attacks against rebels and that Washington would be providing military support to the opposition.
US President Barack Obama separately discussed the Syrian war with European leaders ahead of next week's G8 summit in Northern Ireland, the White House said.
Obama spoke late Friday with British Prime Minister David Cameron, French President Francois Hollande, Italian Prime Minister Enrico Letta and German Chancellor Angela Merkel.
The European Union lifted an embargo on arming the Syrian opposition last month, paving the way for greater Western support for rebels battling to oust President Bashar al-Assad in a civil war that has claimed 93,000 lives.