U.S. President Joe Biden on Sunday called on Islamic Emirate of Afghanistan (IEA) to release a U.S. civil engineer who was abducted two years ago and is believed to be the last American hostage held by the IEA.

Mark Frerichs, a 59-year-old U.S. Navy veteran from Lombard, Illinois, who worked in Afghanistan for a decade on development projects was kidnapped a month before the February 2020 U.S. troop pullout deal was signed and was transferred to the Haqqani network.

Monday marks his second year in captivity.

“Threatening the safety of Americans or any innocent civilians is always unacceptable, and hostage-taking is an act of particular cruelty and cowardice,” Biden said in a statement.

“The Taliban (IEA) must immediately release Mark before it can expect any consideration of its aspirations for legitimacy. This is not negotiable.”

Biden pulled U.S. troops out of Afghanistan in August in a chaotic withdrawal that drew sharp criticism from Republicans and his own Democrats as well as foreign allies and punctured his approval ratings.

Frerichs’ family has criticized the U.S. government for not pressing harder to secure his release. Last week, his sister, Charlene Cakora, made a personal plea to Biden in a Washington Post opinion piece titled, “President Biden, please bring home my brother, the last American held hostage in Afghanistan.”

The United States has raised Frerich’s case in every meeting with the Taliban (IEA), the State Department said in a statement. “We call on the Taliban (IEA) to release  him. We will continue working to bring him home,” U.S. Secretary of State Antony Blinken added in a Twitter post.

U.S. and IEA officials met for the first time since the pullout in October in Doha, Qatar, which had hosted talks on Afghanistan that led to the troop withdrawal.

The Qatari emir was due to visit the White House on Monday on a range of issues that will include global energy security, the White House said last week. Qatar represents U.S. interests in Kabul.