ALEXANDRIA, Va. — A Virginia man will spend at least 25 years in prison after admitting he tried to conduct a suicide bomb attack against the US Capitol.

Amine El Khalifi, 29, an illegal immigrant from Morocco living in Alexandria, pleaded guilty Friday in US District Court, admitting that he plotted with men he thought were Al Qaeda operatives to attack the Capitol. In reality, Khalifi was the target of an undercover FBI operation.

He was arrested in February in a parking garage near the Capitol, wearing what he thought was an explosives-laden suicide vest.The vest, provided by undercover operatives, was inert.

A gun he planned to use to shoot his way past security in the building was also inoperable.

Friday’s plea deal requires the judge to sentence Khalifi to a term of between 25 and 30 years when the sentencing is held Sept. 14. In the plea deal, prosecutors state they will ask for a 30-year sentence.

Prosecutors said Khalifi had revealed his intention to kill Americans to an undercover FBI operative he thought was a member of the Al Qaeda terrorist group.

He spoke of wanting to attack a synagogue and kill Army generals, prosecutors said, before settling on a plot to blow himself up inside the Capitol as an act of martyrdom. Officials have said the public was never in danger.

Khalifi’s lawyer, federal public defender Ken Troccoli, declined to comment after Friday’s hearing.