CNN reported that the warning was issued by the US Departments of State and Defense and conveyed to Ukrainian and European officials late last week.
Two European officials told CNN that the United States had also delivered the warning to Ukrainian military leaders.
The development comes amid growing frustration from US President Donald Trump over Ukraine’s continued attacks on Russian oil refineries, which he says are contributing to rising diesel prices on the international market.
Trump has repeatedly called on both Ukraine and Russia to stop attacks on energy infrastructure.
On Sunday, October 11, 2026, he announced that the two countries had agreed to halt such attacks. However, people close to Ukrainian President Volodymyr Zelenskyy said the announcement came as a surprise to them.
Zelenskyy said Ukraine supported the proposed truce but stressed that Russia must also honour the agreement.
He added that Kyiv was awaiting further clarification from the United States.
