Kerry, speaking after meeting with Russian Foreign Minister Sergei Lavrov on the sidelines of a meeting of Southeast Asian nations in Laos, said there had been progress in recent days on moving forward with the plan.
The proposal would have Washington and Moscow share intelligence to coordinate air strikes against the al Qaeda-affiliated Nusra Front and prohibit the Syrian air force from attacking moderate rebel groups.
In Geneva, U.N. Special Envoy Staffan de Mistura said he aimed to convene a new round of Syria peace talks toward the end of August, quietly scrapping a previous Aug. 1 deadline while keeping some time pressure on the U.S.-Russia deal.
“Our aim, let me say very clearly, is to proceed with a third round of intra-Syrian talks toward the end of August,” de Mistura told reporters after meeting U.S. Syria envoy Michael Ratney and Russian Deputy Foreign Minister Gennady Gatilov.
De Mistura said he strongly hoped Lavrov and Kerry would make concrete and visible progress because that would improve the situation on the ground and the environment for the peace talks, although such progress was not a precondition for talks.
More details of the U.S.-Russia plan needed to be worked out in the next few days, he said.
Kerry has defended the proposal despite deep skepticism among top American military and intelligence officials, including Secretary of Defense Ash Carter and chairman of the Joint Chiefs of Staff Joseph Dunford, over working with Russia.
“My hope is that somewhere in early August we would be in a position to stand up in front of you and tell you what we’re able to do with the hopes it can make a difference to lives of people in Syria and to the course of the war,” Kerry told a news conference in the capital Vientiane.
QUESTIONS ABOUT TRANSPARENCY
During the discussions, he and Lavrov outlined the next stage of implementing the plan, including a series of technical-level meetings to address concerns by the U.S. military and intelligence community.
Kerry’s State Department and White House allies say the plan is the best chance to limit the fighting that is driving thousands of Syrian civilians, with some trained Islamic State fighters mixed in, into exile in Europe, and preventing humanitarian aid from reaching tens of thousands more.
A senior Western diplomat said the lack of transparency of the U.S.-Russia talks was frustrating and – with increased targeting of civilians and hospitals on the ground – it was hard to foresee any deal.
“The Americans are risking a lot for a deal that is as unlikely to be honored as previous engagements the Russians have made,” the diplomat said.
The meeting in Laos comes amid accusations that Russia is behind the hacking of Democratic National Committee (DNC) emails released by Wikileaks on Friday.
Kerry said he raised the issue of the emails with Lavrov during their meeting. Earlier, Lavrov brushed aside the accusations that Russia was involved, saying: “I don’t want to use four-letter words.”
Cyber security experts and U.S. officials have said there is evidence that Russia engineered the release of the emails in order to influence the U.S. presidential election.
The FBI said it was investigating a cyber intrusion at the DNC, which has led to discord as the party’s convention in Philadelphia opens on Monday to nominate former U.S. secretary of state Hillary Clinton as its candidate.
Authors: Lesley Wroughton and Stephanie Nebehay