Defense Secretary Austin makes unannounced visit to Kyiv

WASHINGTON and LONDON -- U.S. Defense Secretary Lloyd Austin arrived in Kyiv Monday morning for an unannounced visit to Ukraine, his second to the country since Russia invaded in February 2022.

He's expected "to meet with Ukrainian leaders and reinforce the staunch support of the United States for Ukraine's fight for freedom," according to a Defense Department statement.

"He will also underscore the continued U.S. commitment to providing Ukraine with the security assistance it needs to defend itself from Russian aggression, while also discussing a long-term vision for Ukraine's future force," the statement said.

Austin was greeted on the platform by U.S. Ambassador to Ukraine Bridget Brink and the defense attaché, Brig. Gen. Kipling Kahler.

The secretary is expected to meet with Ukrainian leaders for high-level talks on topics that include how the U.S. and Ukraine can further bolster their partnership, his office said

Those discussions are also expected to include "ensuring Ukraine's armed forces have the battlefield capabilities they need for both the winter and to defend their country against future Russian threats," the Defense Department said.

Ukrainian President Volodymyr Zelenskyy told reporters last week that deliveries of artillery shells to his country have "really slowed down."

Austin departed from Maryland's Joint Base Andrews on a C-32 airliner early Sunday morning and arrived in Poland Sunday night local time. From there, he took an approximately 11-hour train ride into Ukraine, where he was greeted by Brink and Kahler as he stepped on the platform.

In all, the journey was about 22 hours from Washington to Kyiv.

Austin is traveling with Assistant Secretary of Defense for International Security Affairs Celeste Wallander, Deputy Assistant Secretary of Defense for Russia, Ukraine, Eurasia Laura Cooper and Gen. Chris Cavoli Commander, U.S. European Command and Supreme Allied Commander Europe (SACEUR) who joined them in Poland.

Austin previously visited Ukraine in April 2022, traveling that time with Secretary of State Antony Blinken.

In Kyiv, the pair announced millions more in U.S. security assistance, increased U.S. training for Ukrainian troops and the return of U.S. diplomats to Ukraine. Blinken also announced during that visit that President Joe Biden would formally nominate Brink to serve as envoy in Kyiv.

This is a developing story. Please check back for updates.

ABC News' Tom Soufi-Burridge and Conor Finnegan contributed to this report.