Pete Hegseth said every American should be concerned about the upcoming release of former American Taliban militant John Walker Lindh.

The former Islamist fighter, named “Detainee 001 in the war on terror,” was arrested in 2001, just months after the Sept. 11 attacks and the start of the war in Afghanistan, along with a group of Taliban fighters who were captured by U.S. forces.

Walker Lindh is due to be freed in May, and his release has prompted security concerns, as he's expressed wishes to travel to Ireland while also not denouncing radical Islamic ideology.

Moving to Ireland became an option for Walker Lindh after he obtained citizenship there, while still in prison, thanks to his family’s lineage.

On "America's Newsroom" Wednesday, Hegseth, an Army veteran who served in Iraq and was deployed to Guantanamo Bay as a guard, said this is "lunacy" because it appears that Walker Lindh is as radicalized now as he was in 2001.

"This guy says he loves ISIS, says he loves Al Qaeda, wants to kill Americans, and we're gonna release him?" Hegseth said incredulously.

He said this shows that the U.S. government and institutions are "fundamentally unserious" about protecting Americans and are not prepared for the years-long battle against the ideology of radical Islam.

"This should scare every American, that we still haven't figured out what kind of war we're in," Hegseth said.

He added that Ireland has no way to monitor Walker Lindh's movements once he has secured entry to the country, warning that many of the inmates he guarded at Guantanamo Bay returned to the battlefield upon release.

"It's lunacy," he said.

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