A U.S. air strike killed a former Guantanamo Bay detainee as part of the Trump administration’s expanding counterterrorism campaign in Yemen, the Pentagon said on Monday.

Capt. Jeff Davis, a Pentagon spokesman, said that a man known as Yasir al-Silmi, who was held at the military prison in Guantanamo Bay, Cuba, from 2002 to 2009, was believed dead following a March 2 strike that also killed Usayd al-Adnani, a top operative for al-Qaeda in the Arabian Peninsula (AQAP), in Yemen’s Abyan Governorate.

The strike last Thursday was part of a stepped-up military campaign, including air strikes and expanded ground operations, that the United States has been conducting against AQAP since President Trump took office in January. One of the opening moves of that campaign was a controversial Jan. 29 raid that killed one Navy SEAL and, according to Yemeni accounts, scores of civilians.

Silmi, a Yemeni national who had also gone by the name Mohamed Tahar, was arrested in Pakistan in 2002, and handed over to U.S. authorities in May of that year. While U.S. officials suspected him of having ties to al-Qaeda plots, Silmi, like the vast majority of the more than 700 inmates who have been held at Guantanamo since 2002, was never charged with a crime.

In Dec. 2009, the Obama administration repatriated Silmi, making him one of the very last transfers the U.S. government has carried out to Yemen, long struggling with insecurity and now locked in an extended civil conflict. Shortly after Silmi and five other Yemenis were repatriated, AQAP launched an attempt to blow up a U.S. airliner, one of a series of attacks the group has mounted against the United States.

Officials said Silmi had been known to the U.S. government as an AQAP operative, but he was not believed to be a senior member of the militant group.

The presence of a former U.S. detainee among militants targeted in Yemen may provide additional ammunition to critics of efforts to resettle prisoners from the facility, which President Barack Obama sought and failed to close before he stepped down this year. Some lawmakers have long opposed releasing detainees because of concerns about those men posing a security threat to the United States. The scale of that risk has been disputed by supporters of the transfers.

Davis, speaking to reporters at the Pentagon, said that Silmi was one of the former U.S. prisoners “who clearly had become a recidivist.”

So far, Trump has indicated his opposition to moving prisoners out of Guantanamo, suggesting that suspected militants could instead be brought there for interrogation and detention. In addition to the new operation in Yemen, the administration is also promising intensified activities against the Islamic State and other groups it plans to target as part of its goal of defeating “radical Islamic terrorism.”

The White House is expected to issue a new executive order that would lay out the case for continuing operations at the prison. Today, only 41 prisoners remain at Guantanamo.