President Trump on Tuesday quipped about Canadian Prime Minister Mark Carney becoming the “future Governor of Canada,” reviving an insult previously hurled at his predecessor Justin Trudeau over the president’s push for America’s northern neighbor to become the 51st state.

“I’m working with Governor Gretchen Whitmer [D-Mich.] on trying to save The Great Lakes from the rather violent and destructive Asian Carp, which is rapidly taking over Lake Michigan, and all of the beautiful surrounds,” Trump wrote in his Tuesday Truth Social post.

“I’ll be asking other Governors to join into this fight, including those of Illinois, Wisconsin, Minnesota, Pennsylvania, Ohio, Indiana, New York and, of course, the future Governor of Canada, Mark Carney, who I know will be happy to contribute to this worthy cause,” he added.

Whitmer has been working with Trump to address the issue of Asian Carp fish since last year, when she was at the White House for a meeting on the topic but found herself in front of the press during a “surprise” appearance at one of the president’s executive order signings.

The Michigan governor is in close contact with her counterparts in Canada and has been subject to a heated back and forth between Trump and Carney on a range of initiatives, including the U.S.-Canada bridge, which the president previously threatened to close.

Trump and Carney’s relationship has been fraught at least in part due to the president’s jokes about wanting to make Canada part of the U.S.

Earlier this year, Trump pulled an invitation for Canada to join his Board of Peace after leaders in Toronto shared hesitancy about the group’s mission.

Carney has also slammed the U.S. strikes on Iran, describing the conflict as a “failure of the international order” after urging middle powers to unite after declaring a “rupture” to the world order at the World Economic Forum in Davos, Switzerland.

Although the two leaders have clashed publicly, Carney said it’s different behind closed doors.

“It’s quite different in private,” Carney told the Canadian broadcaster CBC.

“And that creates an ability to work through things, but it’s not easy, let’s be clear.”