By Max Hunder and Tom Balmforth

KYIV (Reuters) -U.S. Secretary of Defence Lloyd Austin announced $100 million in new military aid to Ukraine during an unannounced visit to Kyiv on Monday, pledging long-term American support amid growing concerns about the sustainability of vital U.S. assistance.

Austin announced the aid package after a day of meetings with Ukrainian officials, with the latest tranche including arms such as anti-tank weapons, air-defence interceptors and an additional High Mobility Artillery Rocket System (HIMARS).

Austin, accompanied by the top U.S. general in Europe, was photographed smiling and shaking hands with Ukrainian President Volodymyr Zelenskiy. It marked Austin’s first visit to Kyiv since April 2022.

“The message that I bring you today, Mr. President, is that the United States of America is with you. We will remain with you for the long haul,” Austin told Zelenskiy after an overnight train ride into Ukraine from Poland.

Zelenskiy told Austin that his visit was “a very important signal” for Ukraine.

“We count on your support,” Zelenskiy told Austin.

The United States has provided more than $44 billion in security assistance to Ukraine since Russia launched its invasion in February 2022.

“I think they are prepared for combat in the winter,” Austin told reporters after his meetings.

“They did a great job last year. This year we expect them to be, just based on what… President Zelenskiy has said, them to be even more aggressive,” Austin added.

The trip comes amid increasing division over aid for Ukraine in the U.S. Congress, with a U.S. presidential election coming in November 2024. Some American lawmakers are prioritising aid to Israel even as U.S. defence officials stress that Washington can support both allies simultaneously.

In a statement on Monday, U.S. Secretary of State Antony Blinken appealed for lawmakers to approve more aid.

“It is critical for Congress to take action to support Ukraine by passing the President’s supplemental funding request,” Blinken said.

“Helping Ukraine defend itself … helps prevent larger conflict in the region and deters future aggression, which makes us all safer.”

Privately, some top Ukrainian officials have voiced concern that deliveries of military aid may become less frequent, reflecting broader unease over the levels of support needed to sustain the war against Russia. Ukraine’s budget for next year has a deficit of more than $40 billion which needs to be filled.

STOP-GAP SPENDING BILL

President Joe Biden had asked Congress to approve more money for Ukraine last month. Its omission from a stop-gap spending bill passed by lawmakers last week raised concerns that funding for Ukraine might never be appropriated, especially after the Republican-led House of Representatives passed a bill including assistance for Israel but not Ukraine.

A vocal bloc of Republicans oppose sending more aid to Ukraine. Opponents of the aid have said U.S. taxpayer money should be spent at home, but a majority of Republicans and Democrats in Congress still support aid to Zelenskiy’s government.

A joint Ukraine-U.S. military industry conference in Washington, due to take place on Dec. 6 and 7, is intended to boost Ukraine’s domestic arms production as the war drags towards the two-year mark.

Russia now controls nearly a fifth of Ukraine. The West sent in military equipment and Ukraine mounted a counteroffensive push this year to retake occupied land, but it has not made a big breakthrough.