Ukrainian President Volodymyr Zelenskyy issued a warning to the United States. He said formally siding with Putin would be a "historic mistake." The waiver involved Senator Lindsey Graham's Russia sanctions law.

Zelenskyy said President Trump's waiver showed "really big support for Putin." He also said the waived sanctions were "strengthening Putin's war against us." But he still sees Trump as an ally. Some moves had unsettled Ukraine and its friends in Congress.

The White House said the sanctions could hinder peace talks. Senator James Lankford defended the waiver.

He said it balanced pressure on Russia with United States fuel costs. Congress passed the sanctions law with support from both parties.

Trump signed it in September. He waived it Friday.

The law targeted Russia and buyers of its oil and gas. The waiver came days after a deal with Putin. The deal aimed to release Russian diesel onto global markets.