U.S. Secretary of State John Kerry met with key Russian leaders on Tuesday in an attempt to work past their philosophical differences and find a diplomatic solution to the Syrian civil war.

Kerry met with Russia’s president, Vladimir Putin, and foreign minister, Sergey Lavrov.

The talks came ahead of a planned meeting of the International Syria Support Group (ISSG), a collection of countries looking to put an end to the ongoing conflict in Syria. The nations, which include the United States and Russia, are scheduled to meet this coming Friday in New York.

Russia and the United States haven’t been on the same page about how to end the conflict, particularly about the fate of Syrian President Bashar al-Assad. The controversial leader has been the main point of contention in the conflict, which began with an uprising in 2011 and subsequently led to millions of Syrians fleeing their homes to escape the war-torn nation.

U.S. President Barack Obama has publicly said Assad must be out of office before the war can end. It’s been widely reported that Russia is one of Assad’s biggest allies, and Moscow believes Syria’s residents — and not any other nation — should ultimately get to determine what happens.

Complicating the issue is the fact that the Islamic State terrorist organization has taken control of territory in both Syria and Iraq, and the United States is leading a 65-nation coalition that is conducting airstrikes in the region. Russia has also been carrying out some airstrikes on its own.

Speaking to reporters at a joint news conference with Lavrov, Kerry said the two nations “did reach some common ground today,” but it wasn’t appropriate for him to elaborate further because they ultimately needed the entire ISSG to come together to discuss the future of Syria.

“We are cooperating now in Syria because (the Islamic State) is a threat to all of us,” Kerry told reporters, adding he expected Friday’s ISSG meeting in New York to proceed as scheduled.

Kerry’s visit to Russia came days after a collection of Assad’s critics gathered in Saudi Arabia to and developed a unified vision as to how they could politically resolve the multi-year conflict.

The Syrian Coalition said it’s seeking a new democracy built upon equality, transparency, law and accountability, but took a firm stance that neither Assad nor the members of his current regime could take part in any transitional government “or any future political settlement.”

That coalition wants to meet Assad’s government for peace talks, potentially next month.