President Barack Obama said on Thursday he reserves the right to resort to a range of diplomatic and military options if he gets conclusive proof that the government of Syrian President Bashar al-Assad had used chemical weapons in the country's civil war.
Obama, at a joint news conference with Turkish Prime Minister Tayyip Erdogan, said there was evidence of chemical weapons use in Syria but that it is important to get "more specific information" to confirm this before deciding how to respond.
Erdogan had been expected to push Obama, at least in private, for more assertive action on Syria during a visit to Washington this week, days after car bombs tore through a Turkish border town in the deadliest spillover of violence yet.
But the two leaders showed no sign of friction in their appearance in the White House Rose Garden and sought to project a united front on Syria.
Obama - who has been reluctant to arm Syrian rebels or become enmeshed militarily in the two-year-old conflict - expressed hope that the United States and Russia would succeed in arranging a peace conference that would produce results.
But Obama, who had insisted chemical weapons use would be a "game changer," made clear, however, that Washington was keeping all options on the table, though he did not provide specifics.
"There are a whole range of options that the United States is already engaged in," he told reporters. "And I preserve the options of taking additional steps, both diplomatic and military, because those chemical weapons inside of Syria also threaten our security over the long term as well as our allies and friends and neighbors."
Erdogan said Turkey was in "full consensus" with the United States on the need to end the bloodshed in Syria and for a political transition to a government without Assad.