In its final months, President Joe Biden’s administration has decided to allow US defense contractors to work in Ukraine to maintain and repair Pentagon-provided weaponry, US officials told Reuters on Friday, in a significant policy shift that aims to aid Kyiv’s fight against Russia.

A US official, speaking on condition of anonymity, said the contractors would be small in number and located far from the front lines. They will not be engaged in combat.

They will help ensure US-provided equipment “can be rapidly repaired when damaged and be provided maintenance as needed,” the official said.

Since Russia’s 2022 invasion of Ukraine, the United States has given Kyiv tens of billions of dollars in weaponry. But Kyiv either had to move US-provided weaponry out of the country for heavy repair or rely on video-conferencing and other creative solutions to fix those systems inside the country.

The restrictions in the past have sometimes slowed down repairs and proven increasingly difficult as the US has provided Kyiv with more complicated systems, like F-16 fighter jets and Patriot air defenses, officials say.

A lot of equipment in the country is not being used because it is damaged, a second US official told Reuters.

The move is the latest easing of restrictions by Biden’s administration, which has sought to help Ukraine defend itself against Moscow’s 2 1/2 year-old invasion without becoming directly engaged against nuclear-armed Russia.

A third US official said the decision would move the Pentagon in line with the US State Department and US Agency for International Development, which already have US contractors in Ukraine.

The official added that no US troops would be required to defend contractors in Ukraine, and that issues like safety and risk mitigation would be the responsibility of those companies entering into contracts with the Pentagon.

Some US defense contractors have already gone to Ukraine in small numbers in the past, servicing weapons that weren’t being provided by the Pentagon, the official said.

Given there are already are a “wide array of American companies” who have personnel in Ukraine fulfilling contracts for the Ukrainian government, there would not be a substantial increase in US company employees working on the ground, the first official said.

The decision comes at a critical time for the conflict. Russian forces are advancing at their fastest rate since Ukraine first repulsed their invasion at the outskirts of Kyiv in early 2022. Ukraine, for its part, has launched its first major incursion into Russian territory.

Still, it’s unclear how sustainable the policy shift will be with so little time left in Biden’s administration. President-elect Donald Trump has criticized the scale of US military and financial support for Kyiv and vowed to end the war with Russia quickly, without saying how. Trump takes office on Jan. 20.

As the biggest contributor by far to Kyiv’s war effort, US support has been essential to Ukraine’s survival against a much larger and better equipped Russian enemy.

Moscow’s forces occupy around a fifth of Ukraine, and it is increasing pressure on Kyiv, which is facing problems fielding a strong enough fighting force to stand up to Russia’s steady onslaught – bolstered recently by the addition of North Korean troops.

Ukraine has called on the West to lift restrictions on using missiles to attack deep into Russia, which Kyiv says is necessary to disrupt long-range Russian attacks.

But Biden’s administration has not announced any changes to that policy, which officials say might not be sufficient to change the tide in the war, and which Moscow says would escalate the conflict.