WASHINGTON (AP) — The first U.S. troops to deploy after the Sept. 11 attacks are suffering from radiation exposure that the government has yet to officially recognize 23 years later. They are a final group of 9/11 service members that comedian Jon Stewart, a champion for first responders, can’t leave behind.

Special operations forces were sent to a former Soviet base in Uzbekistan in early October 2001, where they launched the first missions against the Taliban in Afghanistan, including the secret horseback operation depicted in the movie “12 Strong.” Over the next four years, more than 15,000 U.S. troops deployed to Karshi-Khanabad, known as K2.

Troops found clumps of yellow powder scattered near bunkers where Soviet troops had stored missiles. Testing showed it was radioactive uranium, according to a declassified November 2001 Defense Department assessment.

In the years since, thousands of K2 veterans have reported cancers, kidney problems and other medical conditions, some of which are known to be connected to radiation exposure. But exposure from K2 is not covered under a major veterans aid bill known as the PACT Act that President Joe Biden signed in 2022.

“K2 veterans were the tip of the spear. They were the first group deployed in the war on terror, and they are still on a lazy Susan of bureaucratic nonsense, keeping them from getting the benefits and health care that they earned,” Stewart said in an interview this week with The Associated Press.

Stewart is pressing the Biden administration for changes to get the K2 veterans fully covered and he called into a meeting Monday between veterans and the Defense Department’s assistant secretary for health affairs.

A 2001 Army health team site assessment found uranium littered around K2 in “pellets, discrete pockets of yellow residue, and finely distributed throughout the soil.”

“Testing to date implies that the uranium is not depleted uranium but rather an enriched product,” the now-declassified report found.

Despite those records, the Defense Department has not officially identified the base as a location where radiation exposure took place. And the Department of Veterans Affairs has not added it to the presumptive conditions troops experienced there. The White House has said it remains a priority for Biden, but has deferred to the agencies, which say more information is needed.

“President Biden believes veterans harmed by toxic exposures while they were stationed at K2 should have access to the benefits they earned and deserve,” White House spokesperson Kelly Scully said in a statement to the AP.

The Pentagon also said in a statement it “remains committed to thoroughly reviewing all information related to K2” and that “ensuring the health and safety of our service members and veterans remains a top priority.”

VA spokesman Terrence Hayes said in a statement that since the passage of the PACT Act almost 12,000 K2 veterans have been approved for at least one service-related condition and have received an average yearly payment of $30,871 to compensate them for the disabilities they now have.

But K2 veterans have also died waiting for the Pentagon and the VA to recognize their radiation-related illness claims, and further studies and reviews just prolong the process, said Matt Erpelding, who leads the K2 veterans group Stronghold Freedom Foundation.

“It needs to get done now,” said Erpelding, who deployed to K2 as a C-130 pilot in December 2001.

Based on a review of the declassified K2 data, radiation levels documented at K2 in 2001 were as much as 40,000 times what would have registered if the uranium was naturally occurring, said Arjun Makhijani, a nuclear fusion specialist and president of the Institute for Energy and Environmental Research.

Radiation exposure from uranium can damage kidneys, create a risk for bone cancer and affect pregnancies, among other harmful effects, said Makhijani, who previously worked with veterans sickened by radiation at the Bikini Atoll during nuclear weapons tests in the 1940s.

The VA does not have statistics on how many of the 15,000-plus troops deployed at K2 got sick. The veterans grassroots organization has contacted about 5,000 of them, and more than 1,500 reported serious medical conditions, including cancers, kidney and bone problems, reproductive issues and birth defects.

U.S. forces left the base in 2005. Since then, Uzbekistan has taken on a greater role in regional counterterrorism efforts, particularly after the U.S. lost its foothold in Afghanistan after the 2021 withdrawal.

Just over a dozen U.S. troops have been regularly deployed to Uzbekistan over the last few years, according to Pentagon data. Uzbek Gen. Maj. Shukhrat Khalmukhamedov met with Gen. CQ Brown, chairman of the Joint Chiefs of Staff, at the Pentagon on Monday to discuss shared efforts to defeat the Islamic State group and “Uzbekistan’s desire to develop a strategic partnership with the U.S.,” a readout from Brown’s office said.

K2 did not come up, according to a U.S. official who spoke on the condition of anonymity to discuss the private meeting.

The veterans don’t understand why U.S. agencies will not officially acknowledge the radiation exposure, particularly because it’s been reported in agency documents.

“They’re clearly weirdly sensitive about this place,” Stewart said.

Congress obtained detailed environmental assessments of the base and reams of data from the Pentagon and made it public four years ago in a bipartisan effort to get the K2 veterans’ toxic exposure recognized. Rep. Stephen Lynch, D-Mass., and Rep. Mark Green, R-Tenn., recently announced new legislation to that end.

In response to multiple queries by the AP, officials at the White House, VA and Defense Department have pointed to other aspects of expanded care for K2 veterans — both from the PACT Act and supplemental care that the VA announced last month adding more conditions that they face.

When it comes to the radiation exposure, the government refers to a Johns Hopkins study on depleted uranium impact on veterans that won’t be complete until 2031, the 30th anniversary of the attacks.

“Because DOD, and by extension the VA, do not acknowledge it was there, it is a sticking point for every K2 bill or rule and was left out of the PACT Act because it was nonnegotiable,” K2 veteran Mark Jackson said.