All eyes are on a possible meeting between President Donald Trump and Russian President Vladimir Putin on the sidelines of the Asia-Pacific Economic Cooperation (APEC) conference in Vietnam during Trump’s Asia visit.

Trump emphasized the significance of meeting with Putin before leaving for the trip and told Fox News: "Putin is very important because they can help us with North Korea. They can help us with Syria. We have to talk about Ukraine."

While the Russian president's foreign policy aide Yury Ushakov said Thursday that a meeting will take place on the first day of the summit, White House press secretary Sarah Sanders, on the contrary, told reporters aboard Air Force One Friday that a formal meeting would not take place but an informal interaction was still on the cards.

"Regarding a Putin meeting, there was never a meeting confirmed, and there will not be one that takes place due to scheduling conflicts on both sides," CNN cited Sanders as saying. "There is no formal meeting or anything scheduled for them."

She added: "Now, they're going to be in the same place. Are they going to bump into each other and say hello? Certainly possible, and likely. But in terms of a scheduled, formal meeting, there's not one on the calendar and we don't anticipate that there will be one."

The interaction with Putin comes amid a series of investigations into Russia meddling in the 2016 U.S. election. When the two leaders met for the first time on the sidelines of the G20 summit in Germany, Trump, according to Secretary of State Rex Tillerson, pressed Putin on more than one occasion regarding Russian involvement. "President Putin denied such involvement, as I think he has in the past," Tillerson said at the time.

Among the topics that are likely to come up in the interaction, North Korea is thought to be a top priority, after Trump during his address in Seoul called on all nations, "including China and Russia," to implement the sanctions passed by the United Nations including downgrading diplomatic relations with the country and to "sever all ties of trade and technology."

According to Radio Free Europe/Radio Liberty, Trump also hopes that Russia can mount additional pressure on North Korea in light of the Asian country’s mounting nuclear and missile tests.

USA Today stated that another key topic is said to be the Iran nuclear deal — that seeks to limit Iran’s nuclear activities — parts of which Trump wants to strengthen or renegotiate in return for the lifting of international sanctions on the country.

Putin, however, has pledged to remain in the deal and Russian diplomat Dmitry Peskov warned of "very negative consequences" for nuclear proliferation efforts and regional security if the U.S. pulled out of the agreement.

Trump has also delayed implementing sanctions that Congress imposed on Russia for supporting anti-government forces in Ukraine and for Moscow's alleged role in the 2016 presidential election. Meanwhile, Putin has proposed a U.N. peacekeeping force to reduce the violence in Ukraine.

The two leaders are also likely to discuss the situation in Syria, with Moscow and Washington standing on opposite sides over the issue of the Syrian government's alleged use of chemical weapons. While the U.S. and its allies condemned the use of such weapons and sought to use the UN Security Council to mount pressure on Syria, Moscow blocked UN sanctions over the attacks and refused to condemn the Syrian government.

However, Radio Liberty reported that Russian Foreign Minister Sergei Lavrov said on state-run TV this week that any agreement the two might reach about bilateral relations would be undermined by "political infighting."

"They will immediately become an element of internal political fighting, internal political games aimed at making President Trump's life and activities as difficult as possible," he said.