With the United Nations set to meet next week in New York City, John Kerry sounded a warning shot today, pressing for a Security Council resolution demanding Syria hand over its chemical weapons.

"Time is short. Let's not spend time debating what we already know," the secretary of state told reporters at a briefing at the State Department on Thursday.

"Instead, we have to recognize that the world is watching to see whether we can avert military action and achieve through peaceful means even more than what those military strikes promise," Kerry said.

Despite Kerry's allusion to military strikes, momentum for U.S. military action has stalled domestically. President Obama has pledged not to strike Syria without approval from Congress, which opposes military action.

On Monday, the U.N. released its much-anticipated report on the use of chemical weapons in Syria. Kerry said Thursday the report proves Assad's regime is to blame.

"This isn't complicated, when we said we know what is true, we meant it," Kerry said.

Details unveiled by the U.N. about missiles that carried sarin gas in the August attack outside Damascus., Kerry said, prove Assad's culpability for "anyone who puts the dots together."

"Every single data point - the types of munitions and launchers that were used, their origins, their trajectory, their markings and the confirmation of sarin - every single bit of it confirms what we already knew and what we told America and the world," Kerry told reporters.

Next week, Kerry will travel to New York for the U.N. General Assembly, which will be in session starting Tuesday. Kerry pressed for a binding resolution to be passed by the Security Council next week.

"We need to make the Geneva agreement meaningful," Kerry said, referencing the agreement between the U.S. and Russia calling on Syria to hand its chemical weapons over to international control.

Kerry also voiced some cautious optimism about recent comments by new Iranian president Hassan Rouhani, who told NBC in an interview this week that Iran will not pursue a nuclear weapon and is open to diplomacy with the U.S.

"I think Rouhani's comments have been very positive, but everything needs to be put to the test. We'll see where we go. And at the right moment, I think the White House and the State Department will make clear where we're headed," Kerry said, in response to a question as he left the podium.

Kerry did not say whether President Obama might meet with Rouhani in New York-an unlikely possibility, according to one Iran expert.

"It can be an opportune venue for what both sides like to write off as chance meetings, although I would be highly surprised if we saw a sit-down between the two presidents," Suzanne Maloney of the Brookings Institution told ABC News this week.

Earlier today Kerry met with his Chinese counterpart Wang Yi, where he said the two would be discussing Syria. China has joined Russia in vetoing all three U.N. Security Council resolutions on Syria since the conflict began, but has expressed support of the new chemical weapons deal. Kerry said that while the United States appreciates China's support for the deal, it needs its cooperation in the UN.

"We do have differences between our nations and have disagreed sharply over how the international community should respond to the Syrian regime's use of chemical weapons," Kerry said after the meeting. "With negotiations ongoing at the Security Council, we look forward to China playing a positive, constructive, important role."