Washington's top diplomat and defence secretary both visited Kyiv on Sunday, and used the first official US visit to Ukraine since Russia invaded to announce a gradual return of US diplomats and the nomination of a new ambassador, officials said.
Secretary of State Antony Blinken and Secretary of Defence Lloyd Austin travelled to Poland on Saturday then overland into Ukraine on Sunday, where they met President Volodomyr Zelensky and other top Ukrainian officials, a senior State Department official said.
The visit was designed to show Western support for Ukraine and the cabinet secretaries also pledged new assistance worth $713 million for Zelensky's government and countries in the region.
Russia's invasion of Ukraine on 24 February has raised fears in the region of further aggression by Moscow.
It also highlighted the shift in the conflict since Ukrainian forces, armed with a influx of weapons from the West, successfully repelled a Russian assault on Kyiv.
Russian forces have regrouped to try to capture more territory in the southeastern Donbas region, which has allowed foreign leaders visit the capital and some Western nations resume their diplomatic presence in recent weeks. But Washington has been cautious about a return amid sporadic Russian missile attacks on the west of Ukraine.
Officials declined requests from the media to accompany the secretaries into Ukraine, citing security concerns. The officials briefed reporters in Poland on condition the trip not be reported until the delegation was safely out of Ukraine.
Austin will travel on to Germany, where he will host counterparts from more than 20 nations and NATO Secretary General Jens Stoltenberg at the US air base at Ramstein to discuss Ukraine's defence needs, a Pentagon official said.
Zelensky announced the trip himself during a news conference on Saturday, which US officials said was a contingency they had planned for and did not derail the visit.
Blinken and Austin were expected to have met for about 90 minutes with Zelensky, Ukraine's Foreign Minister Dmytro Kuleba, Defence Minister Oleksii Reznikov and other officials.
US diplomats departed the Kyiv embassy nearly two weeks before the invasion by Russia, moving some functions to the western city of Lviv before eventually relocating to Poland.
Diplomats will initially resume 'day trips' across the border to Lviv and officials are accelerating plans to return to the Kyiv mission, the State Department official said.
"There's no substitute for that face-to-face engagement, and of course there is a symbolism to being back in the country," said the official, who briefed reporters in Poland on condition of anonymity.
The official also said that on Monday President Joe Biden will formally nominate Bridget Brink, currently US ambassador to Slovakia, as US ambassador to Ukraine, a post that has been vacant for more than two years.
Blinken and Austin informed Zelensky of more than $322 million in new military financing for Ukraine, bringing the total US security assistance to Ukraine since the invasion to about $3.7 billion, the official said.
"It will provide support for capabilities Ukraine needs, especially the fight in the Donbas," the official said.
"This assistance will also help Ukraine's armed forces transition to more advanced weapons and air defence systems, essentially NATO capable systems."
Nearly $400m in new military financing will also go to 15 other nations in Central and Eastern Europe and the Balkans, the official said.
More than 50 Ukrainians were set to complete training on Monday to operate Howitzer heavy artillery that Washington has begun sending to Ukraine in recent weeks. The move reflects that fighting is now focused in the flatter, more open Donbas region, Pentagon spokesperson John Kirby told reporters in Poland.
Ahead of the visit, Blinken spoke with UN Secretary General Antonio Guterres on Friday to coordinate on the UN chief's visits to Moscow and Kyiv, the official said.