(NewsNation) — As tanks, drones and missiles are sent in droves into Ukraine to equip the country against a Russian invasion, concern grows over the weapons getting into the wrong hands and ultimately being turned on those they are meant to help.

To date, the Biden administration has committed around $13.5 billion in military assistance to Ukraine, from heavy artillery to drones, radar and ammunition.

Just this week, President Joe Biden said he’s sending $2.98 billion in new military aid. In July, the U.S. announced $820 million in military aid, including new surface-to-air missile systems.

“It’s hard to know how prepared they are to really effectively track and maintain all the weapons that really do come into the country,” said Jeff Abramson, senior fellow at the Arms Control Association. “So it’s an open question.”

With the billions of dollars pouring in to bolster their defenses, Abramson said corruption within the Ukrainian government is a concern.

In July, Ukraine President Volodymyr Zelenskyy abruptly fired two top officials after an investigation found employees in their departments allegedly colluding with the Russians.

Abramson said there is a concern for weapons being trafficked, but the illegal flow of weapons is hard to prove.

“It’s inevitable that some of these weapons will end up in the wrong hands,” he said. “The scale is what’s hard to know right now. And that’s why there’s this big push for oversight and monitoring now so that we can get a handle on that.”

NewsNation found a Switchblade drone for sale on the dark web. However, its sale cannot be confirmed.

“It’s the smaller small arms and ammunition. That stuff almost invariably ends up somehow on a black market or leaking out the country,” Abramson said. “The larger weapons systems are a little harder to smuggle.”

According to Abramson, when you see instances where weapons have been illicitly trafficked, the Ukrainians have been pretty quick to say it’s Russian disinformation.

As the conflict in Ukraine enters its sixth month, there’s no question the constant flow of weapons from not only the U.S. but other countries as well has helped the Ukrainian army take on Russia.

Ukrainian forces have held their ground in a war once widely expected to be a lightning conquest by Moscow.

As Ukraine is set to commemorate its 1991 declaration of independence from the Soviet Union, Zelenskyy warned impending Russian attacks could be especially brutal.

In past conflicts, U.S. servicemembers were on the ground, adding to the accountability of weapons allocation.

But even after the chaotic exit from Afghanistan, more than $7 billion worth of U.S.-funded military equipment was left behind, including aircraft, vehicles and rocket-propelled grenade launchers.

In Ukraine, there’s no U.S. military presence on the ground.

Defense Secretary Lloyd Austin admitted that makes accountability more challenging, but added the U.S. put its trust in Ukraine.

“In terms of our ability to track the weapons that are going in, as you know, we don’t have any forces on the ground, so that’s — it’s difficult for us to do,” Austin said. ““We have to depend on the Ukrainians at this point, to, to do the right thing and make sure that they are prudent.”

The Defense Department told NewsNation that the Ukrainians have made some assurances on protecting U.S. equipment.

“The Ukrainians have assured us that they remain committed to the protection of U.S.-origin equipment,” said Robert L. Ditchey II, Department of Defense spokesman. “We continue to work closely together with them to further enhance accountability. Ukraine’s success on the battlefield gives us confidence that what we are providing them is being put to good use.”

However, concerns over that accountability are spreading from the Pentagon to Capitol Hill.

In May, Sen. Rand Paul, R-Ky., teed up a showdown on the Senate floor, objecting to more funding for Ukraine weapons shipments — citing not only inflation fears, but accountability.

“I’d like to modify the bill to allow for a special inspector general,” Paul said of a Ukrainian aid package up for vote. “This would be the inspector general that’s been overseeing the waste in Afghanistan and has done a great job.”

Paul insisted an inspector general be appointed and called on the Biden administration to appoint a watchdog to track the spending.

The Biden administration says the latest Ukraine weapons package to pass Congress included millions of dollars for oversight measures.

“We know that oversight of these funds is critical and it’s something that we baked into the provision of these funds,” said State Department spokesperson Ned Price.

There have currently nine Department of Defense inspector general audits underway and Congress is expecting a written report on the security assistance provided so far.

While the reviews are ongoing, the White House told NewsNation it won’t slow support.

John Kirby, National Security Council spokesperson and former Pentagon spokesperson, told NewsNation that from their indications, they’re going to have a better sense of oversight going forward.

“It’s a war and things can happen,” he said. “In a war, we all recognize that. But we’re working hard with the Ukrainians to make sure that there is good accountability that those weapons don’t end up in the wrong hands.”

The Associated Press contributed to this report.