WASHINGTON (AP) — The grinding war between Ukraine and its Russian invaders has escalated ahead of Donald Trump’s inauguration, with President Joe Biden rushing out billions of dollars more in military aid before U.S. support for Kyiv’s defenses is thrown into question under the new administration.

Russia, Ukraine and their global allies are scrambling to put their side in the best possible position for any changes that Trump may bring to American policy in the nearly 3-year-old war. The president-elect insisted in recent days that Russia and Ukraine immediately reach a ceasefire and said Ukraine should likely prepare to receive less U.S. military aid.

On the war’s front lines, Ukraine’s forces are mindful of Trump’s fast-approaching presidency and the risk of losing their biggest backer.

If that happens, “those people who are with me, my unit, we are not going to retreat,” a Ukrainian strike-drone company commander, fighting in Russia’s Kursk region with the 47th Brigade, told The Associated Press by phone.

“As long as we have ammunition, as long as we have weapons, as long as we have some means to defeat the enemy, we will fight,” said the commander, who goes by his military call sign, Hummer. He spoke on condition he not be identified by name, citing Ukrainian military rules and security concerns.

“But, when all means run out, you must understand, we will be destroyed very quickly,” he said.

The Biden administration is pushing every available dollar out the door to shore up Ukraine’s defenses before leaving office in six weeks, announcing more than $2 billion in additional support since Trump won the presidential election last month.

The U.S. has sent a total of $62 billion in military aid since Russia invaded Ukraine in February 2022. And more help is on the way.

The Treasury Department on Tuesday announced the disbursement of $20 billion — the U.S. portion of a $50 billion loan to Ukraine — backed by frozen Russian assets, before Biden leaves the White House. Leaders of wealthy democracies agreed earlier this year to engineer the mammoth loan to help Ukraine in its fight for survival after Russia’s invasion. Interest earned on profits from Russia’s frozen central bank assets would be used as collateral. Treasury Secretary Janet Yellen said Tuesday that the funds “will provide Ukraine a critical infusion of support as it defends its country against an unprovoked war of aggression.”

Biden also has eased limits on Ukraine using American longer-range missiles against military targets deeper inside Russia, following months of refusing those appeals over fears of provoking Russia into nuclear war or attacks on the West. He’s also newly allowed Ukraine to employ antipersonnel mines, which are banned by many countries.

Biden and his senior advisers, however, are skeptical that allowing freer use of longer-range missiles will change the broader trajectory of the war, according to two senior administration officials who spoke on condition of anonymity to discuss internal deliberations.

But the administration has at least a measure of confidence that its scramble, combined with continued strong European support, means it will leave office having given Ukraine the tools it needs to sustain its fight for some time, the officials said.

Enough to hold on, but not enough to defeat Russian President Vladimir Putin’s forces, according to Ukraine and some of its allies.

Even now, “the Biden administration has been very careful not to run up against the possibility of a defeated Putin or a defeated Russia” for fear of the tumult that could bring, said retired Gen. Philip Breedlove, a former supreme allied commander of NATO. He is critical of Biden’s cautious pace of military support for Ukraine.

Events far from the front lines this past weekend demonstrated the war’s impact on Russia’s military.

In Syria, rebels seized the capital and toppled Russia-allied President Bashar Assad. Russian forces in Syria had propped up Assad for years, but they moved out of the way of the rebels’ assault, unwilling to take losses to defend their ally.

Biden said it was further evidence that U.S. support for Ukrainian President Volodymyr Zelenskyy was wearing down Russia’s military.

Trump, who has long spoken favorably of Putin and described Zelenskyy as a “showman” wheedling money from the U.S., used that moment to call for an immediate ceasefire between Ukraine and Russia.

And asked in a TV interview — taped before he met with Zelenskyy over the weekend in Paris — if Ukraine should prepare for the possibility of reduced aid, Trump said, “Yeah. Probably. Sure.”

Trump’s supporters call that pre-negotiation maneuvering by an avowed deal-maker. His critics say they fear it shows he is in Putin’s sway.