Since Trump's summit with Russian President Vladimir Putin in August failed to yield a breakthrough in the U.S. peace push, Kyiv has been hammering Russian oil refineries with drones while Russian strikes have caused major power outages across Ukraine.

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NATO's eastern flank is also on edge after Poland and Estonia said Russia had violated their airspace with drones and jets last month, eliciting denials from Moscow. There have since been other drone incidents in Germany and Denmark.

A former senior Ukrainian official said Russia and Ukraine were both trying to ramp up pressure and improve their hands ahead of any new window for negotiations, and that they lacked the resources to keep up the current intensity for long.

"I think two (more) months is quite enough for this round of escalation," said the source, who spoke on condition of anonymity.
Zelenskiy is expected, among other things, to press Trump for long-range U.S. Tomahawks that would put Moscow and other major Russian cities within range of missile fire from Ukraine.

Trump has said he could supply the weapons to Ukraine if Putin fails to come to the negotiating table.

Russia, meanwhile, is seeking to revive momentum in U.S.-Russian relations that has been lost since the Alaska summit by underlining shared values, while at the same time vowing a tough response to any U.S. action that might harm it