U.S. federal authorities say they have arrested a man near the U.S. Capitol building who they say was seeking to carry out a terrorist attack.

Law enforcement officials say the suspect, a 29-year-old Moroccan, had sought to use what he thought were explosives in an attack on the Capitol. They say the explosives had been “rendered inoperable by law enforcement and posed no threat to the public.”

The U.S. Capitol Police say the man, identified as Amine El Khalifi, was detained as part of a “lengthy and extensive operation” with the FBI.

He was reportedly in the country illegally and not associated with al-Qaida.

The arrest comes one day after a Nigerian man was sentenced in the United States to life in prison for trying to bring down an Amsterdam-to-U.S. flight on Christmas Day 2009 with explosives hidden in his underwear. U.S. officials blame Umar Farouk Abdulmutallab's plot on the Yemen-based branch of al-Qaida.