WASHINGTON/KYIV — US Army Secretary Dan Driscoll held talks on Monday and Tuesday with Russian officials in Abu Dhabi as part of a new push to end the conflict in Ukraine, Driscoll's spokesman said.

United States and Ukrainian officials are trying to narrow the gaps between them over a peace plan, with core issues still unresolved and Ukraine wary of being strong-armed into accepting a deal largely on Russia's terms.

CNN cited a US official as saying on Tuesday that Ukraine has agreed to the deal with only "minor details "outstanding.

Earlier, Ukrainian President Volodymyr Zelensky said more work needs to be done.

Regarding the Abu Dhabi talks, US Army Lieutenant Colonel Jeff Tolbert, a spokesman for Driscoll, said, "Late Monday and throughout Tuesday, Secretary Driscoll and team have been in discussions with the Russian delegation to achieve lasting peace in Ukraine."

The negotiations were "going well" and "we remain optimistic", he added.

The exact nature of the discussions was not immediately clear, and it was not known who was in the Russian delegation.

A US official said that Driscoll, who has emerged as a point man for US diplomatic efforts on Ukraine, was also expected to meet Ukrainian officials while in Abu Dhabi, the capital of the United Arab Emirates.

Underlining the high stakes for Ukraine, its capital Kyiv was hit by a barrage of missiles and hundreds of drones overnight in a Russian strike that killed seven people and disrupted power and heating systems.

Meanwhile, three people died in Russia's Rostov region in massive Ukrainian strikes.

The US policy toward the Russia-Ukraine conflict has zigzagged in recent months.

A hastily arranged summit between US President Donald Trump and his Russian counterpart Vladimir Putin in Alaska in August raised worries in Kyiv and European capitals that the Trump administration might accept many Russian demands, though ultimately it resulted in more US pressure on Russia.

The latest US peace proposal, a 28-point plan that emerged last week, caught many in the US government, Kyiv and Europe off guard and prompted fresh concerns that the Trump administration might be willing to push Ukraine to sign a peace deal heavily tilted toward Russia.

On Tuesday, Kremlin spokesman Dmitry Peskov acknowledged the continuing work between Ukrainian and US representatives based on the plan, saying Russia will also take part in talks on it for settling the conflict.

The plan remains a "substantive basis" for potential negotiations on the Ukraine crisis, Peskov said.

AGENCIES VIA XINHUA