U.S. President Barack Obama said on Thursday that both diplomatic and military options remain open for Washington in dealing with the Syrian conflict.

"Now, there are a whole range of options that the United States is already engaged in," said Obama at a joint press conference with visiting Turkish Prime Minister Tayyip Erdogan at the White House.

"And I preserve the options of taking additional steps, both diplomatic and military, because those chemical weapons inside of Syria also threaten our -- our security over the long term as well as our allies and -- and friends and neighbors," he noted.

Obama once again pointed out that the United States has seen evidence of the use of chemical weapons inside of Syria, but he also made it clear that he needs "more specific information about what exactly is happening there."

He reiterated Washington's position that the Syrian conflict is an "international issue" and should be addressed by "all the various parties involved."

"It's not gonna be something that the United States does by itself, and I don't think anybody in the region including the prime minister would think that U.S. unilateral actions in and of themselves would bring about a better outcome inside of Syria," he said.

The sense of urgency over the Syrian conflict has heightened following the recent allegations of chemical weapons use in the country and reported Israeli air raids on targets inside of Syria.

The United States and Russia have agreed to sponsor another conference in Geneva by the end of May -- bringing to the table representatives of the Syrian government and the opposition -- to make a fresh bid for peace.

On Monday, British Prime Minister David Cameron, at a joint press conference with Obama at the White House, called for greater efforts to end the protracted conflict in Syria, stressing that " there is no more urgent international task than this." Endi