HANGZHOU, China -- US President Barack Obama and his Russian counterpart, Vladimir Putin, discussed the Syria and Ukraine issues at a meeting here Monday on the sidelines of the 11th Group of 20 summit.

The meeting, which lasted more than an hour, was "longer than planned, "Russian media quoted Kremlin spokesman Dmitry Peskov as saying.

The two leaders discussed Syria and Ukraine before moving on to a one-on-one talk, Peskov said, noting that the meeting went well.

Putin said at a press conference after the meeting that he and Obama had "some alignment" of positions and an understanding of what they could do to de-escalate the situation in Syria.

It can be said that Russia-US efforts in fighting terrorist organizations, including those in Syria, would be significantly improved and intensified, he added.

Both countries are interested in fighting terrorism, Putin said, adding that "the US president is absolutely sincere in striving for a resolution of the Syrian conflict."

Meanwhile, Obama called the meeting "constructive" but not "conclusive."

"Typically the tones of our meetings are candid, blunt, business-like and this one was no different," he said at a separate press conference following the meeting.

However, he said that given the gaps of trust that exist, that's a tough negotiation.

"We haven't yet closed the gaps in a way where we think it would actually work," Obama said.

Earlier Monday, a senior Obama administration official was quoted as saying that the two presidents failed to force a breakthrough in negotiations over a cease-fire in Syria, but have agreed to keep up negotiations.

The two leaders directed their top diplomats to return to talks quickly, likely later this week, the official said.

The United States and Russia have been trying to reach a deal over the Syria crisis. Obama said Sunday that the two sides still have "grave differences," but there is still possibility "to make some progress."

US Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov, who met in this eastern Chinese city on Sunday for Syria talks, launched a fresh round of negotiations on Monday morning, but ended without agreement, US media reported.