Keeping Ukraine's war effort up could be too heavy a lift for Europe alone if Republicans break US support

• Republicans in Congress are holding new US aid to Ukraine hostage with the potential for disastrous effects.
• If the US can't support Ukraine in the near term, aid will fall on a handful of European allies.

As Republicans in the US Congress block new aid packages, Ukraine is looking to its other backers for support.

But its other allies, largely European, may not have enough to offer. If the US can't commit to continue its support, aiding Ukraine could be too heavy of a lift for the war-torn country's other partners alone.

On Tuesday, Ukrainian President Volodymyr Zelenskyy met with US senators to plead for further US assistance, detailing how an empowered Russia would take advantage of a defeated Ukraine and weakened Europe. US President Joe Biden has forecasted a similar scenario, warning that if Russia takes Ukraine, Russian President Vladimir Putin "will keep going," potentially attacking other nations.

Experts, too, have warned that Russia would take advantage of any breakdown of US support Ukraine going into the new year.

"If the West cuts aid to Ukraine, Russia will win," George Barros, the geospatial-intelligence team lead and a Russia analyst at the Institute for the Study of War, told Business Insider.

These assessments, which have so far not been persuasive, paint a rather bleak picture of what could be in store for Ukraine and other countries should US politicians remain polarized on the issue of sending further aid. And while Ukraine does have other supporters to lean on, including NATO and European allies, it's not clear how much those benefactors have to give. Similar to the US, other countries such as the UK, Germany, and France all face depleted stockpiles, limited resources, and little disposable military might.

"If the US fails to provide aid soon, the collapse of the lightly armed, Ukrainian Armed Forces," which are running low on ammunition, could "lead to a slaughter, raping, looting and vengeance of tragic and historic proportions," Dan Rice, the President of American University Kyiv and a longtime advocate for sending weapons, including various controversial cluster munitions to Ukraine, told Business Insider.

It is unclear exactly how things might play out or what atrocities could occur in the process, but such war crimes have been reported in this conflict.

Republicans in Congress have blocked the latest aid package, estimated at roughly $111 billion and including assistance to both Ukraine and Israel, and now refuse to move forward unless it includes strict immigration and border policies.

The politicized push has forced the White House to yield ground, with Biden admitting last week he was willing to "make significant compromises on the border." But it hasn't been enough.

Now, there's only days left before Congress' holiday recess, meaning the clock is ticking for a deal to be made and passed.

Officials and experts have argued that a new batch of US aid is absolutely critical for Ukraine to maintain its current defenses as Russia renews its attacks sectors of the front.

Barros told Business Insider that the current stalemate on the battlefield is highly unstable, and a decision made in the West to either renew support for Ukraine or not could easily tip the scale.

The war has largely been one of attrition. Both sides are expending manpower and munitions at astonishing rates, wearing down each other's armies in exchange for limited territorial gains.

Ukraine has been burning through global ammunition stockpiles, straining the US and its allies. Russia, restricted by international sanctions and its pariah status, has faced similar problems. Putin, too, has largely been hesitant to mobilize the country for a full-fledged war.

Now, it appears that's shifting.

"Russia's military supply situation has been steadily improving," Justin Bronk, a professor at the Royal Norwegian Air Force Academy and senior research fellow for airpower and technology in the military sciences team at Royal United Services Institute, wrote last week in a RUSI blog.

"Artillery ammunition production has almost doubled, and has recently been supplemented by over 1 million shells and hundreds of howitzers from North Korea," he wrote. North Korea worked a deal with Russia earlier this year to support its war effort in Ukraine reportedly in exchange for food, petroleum products, and advanced military technologies.

Some of Ukraine's allies, too, have prioritized ammunition production. The US Army has completely reworked its outputs since the war began and hopes to substantially increase its 155mm artillery production from the current rate of 30,000 a month, already a substantial increase since the start of the war, to 100,000 by the end of 2025.

That boost benefits both the US and its partners, assuming the US is able to support them.

"Getting to those higher production rates is kind of a win-win," Douglas R. Bush, the assistant secretary of the Army for acquisition, logistics, and technology, explained to Business Insider. "You can support Ukraine or Israel more, but it also means that we can rebuild our stocks much faster than if we don't make those investments."

Other NATO allies, too, have ramped up ammunition production in light of the war in Ukraine, but there are concerns. Earlier this year, the head of NATO's military committee sounded the alarms on depleted weapons supplies, warning there was little left to offer Ukraine.

"The bottom of the barrel is now visible," Adm. Rob Bauer of the Netherlands, the chair of the NATO Military Committee and NATO's most senior military official, said in October.

"We give away weapons systems to Ukraine, which is great, and ammunition, but not from full warehouses," he added. "We started to give away from half-full or lower warehouses in Europe," which are now running low, too.

Even as Ukraine's European allies hustle to get it what it needs, it is going to complicate things if the US, which accounts for the lion's share of aid Ukraine receives, doesn't continue its support.

According to the Kiel Institute for World Economy Ukraine Support Tracker, the US has been the largest individual donor of military aid to Ukraine since the war began, committing approximately 43.86 billion Euros, or $47.33 billion at the latest conversion rate, from late January 2022 to October 2023. The next largest individual donor of military aid, Germany, spent $18.48 billion. The UK sent $7.09 billion Euros.

The European Union as a larger grouping, though, is a strong backer. Of all heavy weapon commitments from late January 2022 to October 2023, the US accounts for 43%, while the EU countries and institutions account for 47%. Those contributions, however, have been just enough to secure a continued stalemate.

That means that if the US, were to turn off the tap, it could have disastrous consequences for Ukraine's war effort, cutting military aid in half.

It remains to be seen if Congress can get new assistance passed in the eleventh hour, but the uncertainty is still raising concerns.

"Without that Western aid, Ukraine's ability to continue fighting is deeply in question," David Silbey, an associate professor of history at Cornell University specializing in military history, defense policy and battlefield analysis, said in an emailed assessment. "They simply don't have the resources to build the massive amount of munitions needed to continue fighting. Zelenskyy is talking for his life and his country's."

After meeting with Zelenskyy on Tuesday, House Speaker Mike Johnson told reporters: "I have asked the White House since the day that I was handed the gavel as speaker for clarity. We need clear articulation of the strategy to allow Ukraine to win. Thus far, their responses have been insufficient."