On his way to the G20 summit in Argentina, President Trump abruptly canceled his planned meeting with Vladimir Putin.

Tweeting his disapproval of Russia's treatment of Ukraine and casting new uncertainty over U.S.-Russian ties.

His decision only an hour after he said this about the meeting: (SOUNDBITE) PRESIDENT DONALD TRUMP: “I think it’s a very good time to have the meeting…” Trump said he pulled out due to tensions over Russian forces opening fire on Ukrainian navy boats and then seizing them and their crew on Sunday near Crimea, which Russia annexed from Ukraine in 2014.

Trump’s decision also came hours after his former lawyer Michael Cohen pleaded guilty on Thursday to lying to Congress about working on a proposed Trump real estate project in Russia while Trump was running for president.

It would’ve been the first summit between the leaders since their infamous press conference in Helsinki in July.

The decision to cancel the meeting appeared to catch the Kremlin by surprise.

Earlier Thursday Russia said Washington had confirmed the meeting was on.

The Kremlin's spokesman said that if true, Putin would have some extra time for a useful meeting at the G20 summit.