As a member of Diplomatic Security stands watch through the glass at right, U.S. Secretary of State John Kerry makes a statement to the press regarding his meeting with Russian Foreign Minister Sergey Lavrov. (Jacquelyn Martin/AP)

—A proposed peace conference on Syria will likely not happen until at least September, Secretary of State John F. Kerry said Tuesday after meeting here with Russian Foreign Minister Sergei Lavrov.

Kerry spoke privately with Lavrov for nearly two hours outside an Asian security meeting that both diplomats are attending. He said in a statement that he concluded from the conversation that both the United States and Russia are “serious, more than serious, [and] committed” to ending the bloody civil conflict in Syria and working toward a negotiated peace.

“We both agreed that our countries have an ability to make a difference if we can pull together in that effort,” Kerry said. He declined to take questions from reporters.

Lavrov put a somewhat different spin on the meeting, telling the Russian media that Kerry had recognized that “consolidation” of the disparate Syrian opposition is the most important goal to achieve before peace talks can take place.

Under an agreement reached exactly a year ago in Geneva and endorsed by international governments including Russia and the United States, Syria’s opposition has proposed a meeting of negotiating teams whose members were chose “by mutual consent” to establish a transitional government. The United States, which has said no end to the Syrian war is possible unless President Bashar al-Assad cedes power, has since made clear that the “mutual consent” clause ensured that Assad would not be involved.

Russia, Assad’s main diplomatic and military backer, has said that barring the Syrian leader from negotiations is an unacceptable precondition. In a meeting in Moscow in May, Kerry and Lavrov brushed over that disagreement and proposed that a second Geneva meeting take place within weeks between opposition and government representatives.

The proposed meeting has been repeatedly postponed, not only over the question of Assad’s attendance, but because the opposition—riven by disagreements over its own leadership and attendance—has never chosen a negotiating team or officially agreed to be present.

In the meantime, the United States and other opposition backers are trying to reverse a successful military offensive by Assad’s military forces, aided by Hezbollah and Iranian militia forces, and have increased their financial and weapons supplies to the rebels. Senior administration officials have said they believe any peace meeting would have a better outcome if it took place after the rebels established military supremacy, or at least balance.

Kerry on Tuesday appeared to reject the importance of righting the military balance before any negotiation, however, saying that “whether the Assad regime is doing better or the opposition is doing better is frankly not determinative” of that outcome,” referring to a peace deal, “because that outcome requires a transition government.”

The Tuesday meeting was the first face-to-face encounter between Kerry and Lavrov since the Obama administration announced its new policy of direct military support to the rebels in June.

Kerry said that he and Lavrov had “narrowed down some of the options with respect to the potential” of the conference and that “we both agreed that it should happen sooner rather than later.”

But he said that a scheduled high-level meeting between Russia and the United States in July” would make that month difficult, “and obviously August is very difficult for Europeans and others, so it may be somewhat thereafter.”

Following their meeting, Kerry said he “thought it was important to note that the foreign minister believes as I do, and as I think President Obama and President Putin believe, that there are two countries that can have the most significant difference on this question. They are Russia and the United States.”

“It was clear to me,” he said, that “what we both wanted to ascertain from each other is the level of seriousness and capacity to be able to do this.”

Lavrov said, “the results of the meeting were useful, and we agreed on how to move forward on the basis of what we reached.” He said that they also discussed Obama’s upcoming visit to Russia during the September G-20 meeting.