Donald Trump threatened Tuesday to cancel a meeting with Vladimir Putin at the G20 summit this week in response to Russia’s aggression towards three Ukrainian ships.

Trump told The Washington Post he was considering calling off the planned sit-down in Buenos Aires, pending a report on the situation from his national security team.

“I am getting a report on that tonight and that will determine what happens at the meeting,” he said. “Maybe I won’t even have the meeting,” Trump added.

Trump told the newspaper Russia’s actions were a cause for concern. “I don’t like that aggression,” he said. “I don’t want that aggression at all.

The comments represented a harder tone from Trump on the maritime drama Sunday, in which Russian forces fired on and seized two Ukrainian gunboats and a tug in the Kerch Strait, detaining 24 Ukrainian seamen and wounding at least three.

Trump had initially given a more muted response, saying Monday that he did “not like what's happening either way.”

Putin’s spokesman Dmitry Peskov said Wednesday that the meeting was still planned to go ahead.

“The meeting has been finalized,” he told reporters. “We have no other information from our U.S. counterparts.”