Trump called the decision made by Biden last month “stupid.” He also expressed anger that his incoming administration was not consulted before Biden made the move. With the loosening of the restrictions, Biden gave Ukraine long-sought permission to use the Army Tactical Missile System provided by the U.S. to strike Russian positions hundreds miles from its border.

“I don’t think that should have been allowed, not when there’s a possibility — certainly not just weeks before I take over,” Trump said during at a wide-ranging news conference at his Mar-a-Lago resort. “Why would they do that without asking me what I thought? I wouldn’t have had him do that. I think it was a big mistake.”

Trump’s withering criticism of the Biden administration’s move comes as the Democratic administration aims to push every last dollar already designated for Ukraine out the door to help repel Russia’s invasion before Trump takes office on Jan. 20, with future aid uncertain.

But even as Biden tries to surge weaponry and other aid to Ukraine in his final five weeks in office, the moment underscored that it’s Trump who holds the most significant influence over how Ukraine can use its U.S.-provided arsenal in the long run. It’s a critical piece of leverage he could use to try to follow through on his campaign pledge to bring about a swift end to the conflict.

Asked if he would consider reversing the Biden administration decision, Trump responded: “I might. I think it was a very stupid thing to do.”

The White House pushed back on Trump’s criticism, noting that the decision was made after months of deliberations that started before last month’s election.

“All I can assure you is that in the conversations we’ve had with them since the election, and we’ve had at various levels, we have articulated to them the logic behind it, the thinking behind it, why we were doing it,” White House national security spokesperson John Kirby said of the current administration’s coordination with the outgoing administration.

Trump’s relationship with Russian leader Vladimir Putin has been scrutinised since his 2016 campaign for president, when he called on Russia to find and make public missing emails deleted by Hillary Clinton, his Democratic opponent. Trump publicly sided with Putin over U.S. intelligence officials on whether Russia had interfered in the 2016 election to help him, and Trump has praised the Russian leader and even called him “pretty smart” for invading Ukraine.

Vice President-elect JD Vance has said that while the U.S. has differences with Russia, it was counterproductive to approach Moscow as an enemy.

Trump on Monday reiterated his call on both Ukrainian President Volodymyr Zelenskyy and Russian President Vladimir Putin to negotiate an end to the war, calling the death and despair caused by the conflict “carnage.”

But Trump also appeared to acknowledge that finding an immediate endgame to the war — something he has previously said he could get done within 24 hours of taking office — could be difficult.

“I think the Middle East will be in a good place,” Trump said, referring to the conflict in Gaza and an unsettled Syria following the ouster of Bashar al-Assad. “I think actually more difficult is going to be the Russia-Ukraine situation.”

Trump declined to say whether he has spoken with Putin since the election.

Zelenskyy met with Trump in Paris earlier this month, while the president-elect was visiting France for the reopening of the Notre Dame Cathedral. Zelenskyy and other Ukrainian officials have been making a forceful effort to get Trump to maintain support for Ukraine.

But the situation on the ground in Ukraine continues to remain complicated as both sides wrestle for a battlefield advantage that will give them leverage in any negotiations to end the nearly three-year war.

The Pentagon last week unveiled U.S. intelligence that predicts Russia could again launch its lethal new intermediate-range ballistic missile against Ukraine soon.

Putin deployed the missile for the first time last month days after Biden loosened the restrictions on Ukraine. Putin warned the West that Russia’s next use could be against Ukraine’s NATO allies who allowed Kyiv to use their longer-range missiles to strike inside Russia.

Biden agreed to loosen the restrictions after Zelenskyy and many of his Western supporters had pressed Biden for months. They argued that the U.S. ban had made it impossible for Ukraine to try to stop Russian attacks on its cities and electrical grids.

The outgoing president ultimately made the decision last month amid concerns about Russia deploying thousands of North Korean troops to help it claw back land in the Kursk border region that Ukraine seized this year.