President Trump and his Russian counterpart, Vladimir Putin, are expected to meet on the sidelines of a summit meeting in Vietnam on Friday, but US officials are still questioning whether the two leaders have enough to talk about to justify a formal sit-down.

​​Secretary of State Rex Tillerson, speaking ​Thursday ​to reporters ​​in Beijing, where Trump met with Chinese President Xi Jinping, said there​ was never a formal agreement between the two countries ​for a meeting ​and added that ​it would only be warranted if Trump and Putin have something ​”substantive” ​​to ​discuss.

​”We have been in contact with them, and the view has been if the two leaders are going to meet, is there something sufficiently substantive to talk about that would warrant a formal meeting​,” Tillerson said. “And so I would just say there’s been no conclusion made on that.​”​

But he said since they’ll both be at the Asia-Pacific Economic Cooperation ​summit​, it’s likely they would grab a moment.

​”Clearly the leaders are going to be at the summit together. It wouldn’t be at all unusual if they ended up with some kind of a pull-aside​,” he said. ​

Tillerson listed a number of topics for discussion — including trying to find a solution to the ongoing crisis in Syria, the presence of Islamic State terrorists in the Middle East and Russia’s incursion in Ukraine.

Asked about Moscow’s meddling in the 2016 presidential election, Tillerson said: “It stays on that list.”

​Kremlin spokesman Dmitry Peskov ​also ​said that an agenda was still under discussion, but he thought the two presidents would cross each other’s path ​at the summit in Danang.

“As for the content of the meeting, there is no agreed agenda,”​ ​he said​, according to reports in Russian media outlets.

​Trump and Putin had their first face-to-face meeting in July at the G-20 summit in Germany​,​ and the president pressed the Russian leader about interfering in the election.

But Putin denied any involvement.

Trump is in the midst of a 12-day trip to five Asian nations.

During earlier stops in Japan and South Korea, he pressed the leaders of those countries to work together against the threats posed by North Korea.

In discussions with the Chinese president, Trump sought his help in isolating the regime by fully enforcing international sanctions against Kim Jong Un’s government.

Trump also wants Russia to squeeze Kim.

“We want Putin’s help on North Korea, and we’ll be meeting with a lot of different leaders,” Trump said aboard Air Force One as he set off on his Asian trip.

With Post wires