"It's crazy what's taking place. It's crazy. I disagree very vehemently with sending missiles hundreds of miles into Russia. Why are we doing that? We're just escalating this war and making it worse. That should not have been allowed to be done," Trump said in an interview published on Thursday to mark his being named Time's Person of the Year.
President Joe Biden last month lifted the US ban on Ukraine using US-supplied longer-range missiles for strikes deep inside Russia, his latest attempt to boost Kyiv in its battle to repel a Russian invasion force from his country.
President-elect Donald Trump met with Ukraine President Volodymyr Zelenskiy in Paris. (AP PHOTO)
The decision came after pleas from Ukraine President Volodymyr Zelenskiy. The White House cited Russia's deployment of 15,000 North Korean troops along the battlefront as the main reason why Biden changed his mind.
Trump has said he would like to bring a quick end to the nearly three-year-old war but has been cagey on the details. He told Time he had a "very good plan" to help but that if he reveals it now "it becomes almost a worthless plan."
Pressed on whether he would abandon Ukraine, Trump said: "I want to reach an agreement, and the only way you're going to reach an agreement is not to abandon."
He said the entry of North Korean troops into the picture was a "very complicating factor."
Trump, who takes office on January 20, met last weekend with Zelenskiy and French President Emmanuel Macron in Paris. Trump's promise to end the conflict swiftly has raised concerns in Kyiv that it could be largely on Moscow's terms.
President-elect Donald Trump refused to say if he had talked to Russian President Vladimir Putin. (AP PHOTO)
Sources told Reuters that Zelenskiy used the meeting to explain Ukraine's need for security guarantees in any negotiated end to the war with Russia. He has long sought NATO membership.
Trump told Time that the number of people dying in the conflict, especially in the last month, was "staggering."
"I'm talking on both sides. It's really an advantage to both sides to get this thing done," he said.
Asked whether he would cut US military and humanitarian aid to Ukraine if Kyiv did not agree to a peace deal, Trump said, "I think I have a very good plan to help, but when I start exposing that plan, it becomes almost a worthless plan."
The war is entering what some Russian and Western officials say could be its final and most dangerous phase as Moscow's forces advance at their fastest pace since the early weeks of the conflict.
Russia fired a hypersonic ballistic missile known as the Oreshnik at the Ukrainian city of Dnipro on November 21. President Vladimir Putin cast the move as a response to Ukraine's first use of US ATACMs ballistic missiles and British Storm Shadows to strike Russian territory with Western permission.
Washington says more deliveries of US air defence exports to Ukraine are on the way to the country.
The United States last Saturday unveiled a $US988 million ($A1.5 billion) aid package of new arms and equipment to Ukraine.
Asked whether he had spoken to Putin since his election, Trump declined to answer, saying, "I can't tell you. I can't tell you. It's just inappropriate."
