Just months after a controversial meeting in Helsinki, Donald Trump and Vladimir Putin are set to meet in private once again.

The Kremlin announced Thursday that the two leaders have planned a one-on-one meeting during the upcoming G-20 summit this weekend. As NBC News reported, the two will hold a private discussion in Buenos Aires before being joined by other world leaders.

The meeting comes just months after Trump and Putin met in secret in Helsinki, with Trump afterward accepting Putin’s position that Russia did not meddle in the 2016 presidential election — against the findings of his own American intelligence agencies. The meeting itself took place in private, with Trump not allowing any other Americans in to hear what was being discussed.

As CNBC noted at the time, the meeting sparked an international backlash. The Guardian said that their private meeting was “nothing short of treasonous,” and the New York Daily News called Trump’s statements “open treason” in a front-page headline.

It was not clear if anyone else would be allowed in the upcoming meeting between Trump and Putin during the G-20 summit.

The current meeting between Donald Trump and Vladimir Putin also comes amid growing aggression from Russia toward Ukraine. Despite already facing international sanctions for annexing Crimea in 2014, Russia has continued to make advancements toward its western neighbor. It sparked an international crisis this week by attacking and then seizing three Ukrainian vessels that were passing through a narrow waterway connecting the Black Sea to the Sea of Azov, NBC News reported. The Russian vessels surrounded two light military ships and a tugboat, eventually opening fire and seizing the vessels, taking the onboard soldiers captive.

Trump and Putin plan to meet this Saturday, according to a leaked Kremlin doc https://t.co/EcFIHmN1S8 — The Daily Beast (@thedailybeast) November 29, 2018

The attack led Ukrainian President Petro Poroshenko to declare martial law in the regions adjacent to Russia, saying that there is a real threat of a land invasion.

The meeting at the G-20 summit will be the fourth formal meeting between Putin and Trump, who has become increasingly vocal about the ongoing Russia investigation. As Robert Mueller’s team continues to move closer to Trump’s inner circle, the president has responded with repeated attacks calling it a witch hunt and accusing the lifelong Republican Mueller of being an “angry Democrat.”

In the upcoming meeting, Donald Trump and Vladimir Putin are set to discuss their joint anti-terrorism efforts as well as disarmament and how to create better relations between the United States and Russia, a Kremlin spokesperson said.