KYIV, Ukraine — U.S. Defense Secretary Lloyd Austin made an unannounced visit to Kyiv on Monday in a high-profile push to keep money and weapons flowing to Ukraine even as U.S. and international resources are stretched by the new global risks raised by the Israel-Hamas conflict.

Austin, who traveled to Kyiv by train from Poland, met with President Volodymyr Zelenskyy, Defense Minister Rustem Umerov and Chief of Staff Gen. Valerii Zaluzhnyi.

Accompanying Austin in Kyiv was Gen. Christopher Cavoli, who heads U.S. European Command and serves as NATO’s Supreme Allied Commander Europe. It was Cavoli’s first visit to the Ukrainian capital since the full-scale Russian invasion in February 2022.

While there Austin announced the Pentagon would be sending an additional $100 million in weapons to Ukraine from U.S. existing stockpiles, including artillery and munitions for air defense systems. The package also includes another High Mobility Artillery Rocket System or HIMARS.

Austin said Ukraine’s effort to defeat Russian forces “matters to the rest of the world” and that U.S. support would continue “for the long haul.”

Zelenskyy said Austin’s visit was “a very important signal” for Ukraine. “We count on your support,” Zelenskyy said, thanking Congress as well as the American people for their backing.

“Without U.S. assistance we can’t simply not stop the Russian invasion, we can’t survive,” said Dmytro Lubinets, the Ukrainian parliament’s commissioner for human rights. “We paid for the will to be independent every day with our health and lives, but we don’t want to simply die without military [and] financial assistance. It’s not only my position — I can confirm that this is the position of 99% of our population.”

This is Austin’s second trip to Kyiv since Russia’s 2022 invasion, but he is making it under far different circumstances as the world’s attention is drawn to the Middle East and signs of fatigue set in with the almost 21-month, Russia-Ukraine war.

Austin’s first visit occurred in April 2022, just two months after the start of the war. At the time, Ukraine was riding a wave of global rage at Moscow’s invasion, and Austin launched an international effort that now sees 50 countries meet monthly to coordinate on what weapons, training and other support could be pushed to Kyiv.

But the conflict in Gaza could pull attention and resources from the Ukraine fight. The U.S. has worked feverishly since the Oct. 7 attacks by Hamas on Israel, and the weeks of devastating bombardment on Gaza by Israel that has followed, to prevent the conflict from turning into a regional war. Even as Austin stood in St. Michael’s Square in Kyiv, the first question asked at a news briefing at the end of the short visit was about Israel’s use of U.S.-provided weapons in that conflict, instead of about Ukraine.

Both conflicts have already seen significant U.S. military support. To back Israel and to keep that conflict from spreading, the U.S. has already committed two carrier strike groups, scores of fighter jets and thousands of U.S. personnel to the Middle East and has had to shift its force posture and conduct airstrikes against Iranian-backed militant groups that are now hitting U.S. bases in Iraq and Syria on a regular basis.

Addressing the joint demands from Israel and Ukraine, a senior defense official told reporters ahead of Austin’s arrival in Kyiv that the countries are facing “two different kinds of fights.”

“There is some overlap,” the official said, speaking on the condition of anonymity to discuss sensitive security matters. “But where there is overlap in certain kinds of ammunition … there is no reduction in provision of capabilities.”

For Ukraine, the U.S. has already provided more than $44 billion — and allies have sent an additional $35 billion — in weapons packages that range from millions of bullets to air defense systems, advanced European and U.S. battle tanks and, finally, pledges for F-16 fighter jets.

But Ukraine still needs more, and after almost 20 months of shipping arms to Ukraine, cracks are beginning to show. Some European countries such as Poland have scaled back support, noting their need to maintain adequate fighting ability to defend themselves.

Ukrainian officials have strongly pushed back on suggestions they are in a stalemate with Russia after a long-awaited counteroffensive over the summer did not radically change the battle lines on the ground. In a visit to Washington last week, Andriy Yermak, head of the president’s office, provided no details but confirmed that Ukrainian forces had finally pushed through to the east bank of the Dnieper River, which has essentially served as the immovable front line between Ukrainian and Russian forces for months.

However, as winter sets in it will become more difficult for either side to make large gains because of ground conditions. That could further work against Ukraine if U.S. lawmakers perceive there is time to wait before more funds are needed. Ukraine and the U.S. expect that this winter Russia will go after Ukraine’s infrastructure again, like the power grid, making air defenses critical.

Fred Kagan, a senior resident scholar at the American Enterprise Institute, said it would be a mistake to think there is time to wait.

“If we stop providing aid to Ukraine, it’s not that the stalemate continues. The aid is actually essential to preventing the Russians from beginning to maneuver again in ways that can allow them to defeat Ukraine,” Kagan said. “So the cost of cutting off aid is that Russia wins and Ukraine loses and NATO loses.”

Further complicating the support is that the Pentagon has only a dwindling amount of money left in this year’s budget to keep sending weapons to Ukraine, and Congress is months late on getting a new budget passed and has not taken up a supplemental spending package that would include Ukraine aid.

Pentagon officials have said they are now “metering out” Ukraine assistance as the stockpile of available funds dwindles. Despite the growing challenges, officials traveling with Austin said the United States at least “for some time” would be able to continue sending aid, including longer-range weapons and artillery ammunition, which are a cornerstone of Ukraine’s military strategy.

The Pentagon can send about $5 billion more in weapons and equipment from its own stocks. But it only has about $1 billion in funding to replace those stocks. As a result, recent announcements of weapons support have been of much smaller dollar amounts, such as the $100 million package announced in Kyiv by Austin, than in months past.

“You have seen smaller packages, because we need to parse these out,” Pentagon deputy press secretary Sabrina Singh said Thursday. “Because we don’t know when Congress is going to pass our supplemental package.”

Officials have been urging Congress to provide additional money, but a growing number of Senate Republicans have opposed additional Ukraine aid without securing support for other unrelated provisions, such as stricter immigration laws and additional funding for border control. A stopgap spending bill passed last week to avoid a government shutdown during the holidays did not include any money for Ukraine.

In a recent letter to U.S. lawmakers, top Biden administration officials emphasized the importance of budgetary support to Kyiv, warning that “reducing or delaying direct budget support will imperil Ukraine’s military efforts.”

Under Biden’s proposal, some $45 billion would be directed to Ukraine’s military and the remainder would go to economic and humanitarian assistance, including direct budget support that would pay salaries for teachers and hospital workers and finance other basic services to keep the country functioning while most resources are diverted to the war.

Biden proposed including that funding, along with about $14 billion in funding for Israel, in a massive supplemental package, but House Speaker Mike Johnson (R-La.) has resisted joint action on the two conflicts. Instead, Johnson has sought to split the proposals and tie assistance to Israel to huge cuts for the Internal Revenue Service.

In an opinion piece in The Washington Post last week , Biden argued that instability in Europe would eventually draw in the United States, as it had in the past. U.S. assistance to Ukraine now “prevents a broader conflict tomorrow,” he wrote. Information for this article was contributed by Tara Copp and Felipe Dana of The Associated Press and by Missy Ryan, Siobhán O’Grady and Emily Rauhala of The Washington Post.