President Donald Trump plans to meet with world leaders on the sidelines of the G20 summit in Argentina this week, including with the heads of Japan, Germany, and China. But there’s one meeting he may cancel — a chat with Russian President Vladimir Putin.

In an interview with the Washington Post on Tuesday, Trump said he might scrap the meeting over Russia’s attack on three Ukrainian ships in a vital waterway two days earlier.

The incident, in which Russian vessels rammed into and shot at Ukrainian warships, seriously injured at least six of Kiev’s sailors.

“Maybe I won’t even have the meeting,” Trump said, adding that he would wait for a “full report” about the altercation before making his decision. It’s a bit of a reversal for the president, who on Monday failed to blame Russia for the incident during an interview with reporters.

While Trump didn’t fully commit to trashing the Putin reunion, his comments are still striking — although some experts don’t really think he’s sincere.

“I think this statement is a way for Trump to offer at least some reaction to the incident in the Kerch Strait, but not going so far as to release an official statement condemning the incident,” Rachel Rizzo, an expert on European affairs expert at the Center for a New American Security, told me. “Saying he may or may not meet with Putin is an empty threat. Of course he’ll meet with him.”