(NewsNation) — Documents obtained by NewsNation suggest a suicide bombing at the Kabul, Afghanistan, airport two years ago that killed 13 U.S. service members may have been preventable.

Gold Star father Darin Hoover, whose son Staff Sgt. Darin Taylor Hoover was killed in the attack, says it’s “infuriating” to learn there may have been opportunities to take out the terrorist cell that carried out the bombing.

“That’s the frustrating part: We’re finding out all of these different tidbits of information, and it’s coming out in a slow, drip drip kind of way,” Hoover said Monday on “Elizabeth Vargas Reports.” “It’s infuriating, frankly, that they actually had three opportunities to take out that bomber, or the cell that was working on it, and didn’t take the opportunity to do it.”

In the two years since the attack at Abbey Gate, the Pentagon has asserted it was unavoidable. But NewsNation has obtained Pentagon documents — including sworn statements from military members who were there — that suggest otherwise.

The documents revealed that days before the attack, the Pentagon knew the exact location where the ISIS-K operatives expected to have played a role in the attack were stationed.

In one interview with a servicemember whose name is redacted, the servicemember said, “Intelligence officers at the Kabul Airport knew that ISIS-K was staging in a hotel 2-3 kilometers west of the airport.”

Per the documents, Lt. Gen. Chris Donahue reached out to the Taliban to ask them to conduct an assault on the ISIS targets at the hotel, but the organization did not choose to engage.

The documents raise questions about the Kabul airport bombing and the actions taken — or not taken — by U.S. military personnel that day. Earlier this year, a former Marine sniper wounded in the attack testified to Congress that his team believed it had identified the suicide bomber earlier that day, prior to the attack.

Sgt. Tyler Vargas-Andrews told the House Foreign Affairs Committee in March that his team was not given authorization to take out the suspected threat due to military leadership’s uncertainty as to who held authority to give the go-ahead.

Now, Hoover and other Gold Star families of those killed in the attack are pressing the Pentagon for more transparency.

“We’re looking for justice — absolute justice,” Hoover said. “The things we’re looking for is where the breakdown was, who was in charge. Was it the Department of Defense, was it the State Department, was it the White House? We’ve got boots on the ground telling them exactly what’s going on, and it’s being denied at whatever level it was.”

The Pentagon did not answer specific questions about the documents but maintained in a statement that the attack was unavoidable.

“U.S. military commanders on the ground in Afghanistan made the best decisions and provided their best military advice based off what was known at the time and leaders took appropriate action in response to reported threat streams,” the statement reads in part.

NewsNation’s Joe Khalil and Zaid Jilani contributed to this report.