Deputy Secretary John Tien is retiring from the Department of Homeland Security after serving for just under two years, marking the latest major departure to hit the agency.

Tien has served in the capacity since June 24, 2021, and is the first Asian American to be confirmed for the position. He had previously served as chief operating officer at Citigroup, and before that on the National Security Council in the Obama administration as senior director for Afghanistan and Pakistan from 2009-2011, and for the Bush administration as director for Iraq from 2008-2009.

During the Clinton administration he served as a White House fellow in the Office of the U.S. Trade Representative. He is also a military veteran with 24 years of service and three combat tours of duty to Iraq. His retirement date is July 20.

In an internal email sent to DHS employees on Tuesday morning and seen by Fox News Digital, Tien thanked DHS Secretary Alejandro Mayorkas "for having the confidence in me to support my nomination to President Biden and even more so, to empower and enable me to ‘co-lead’ the Department with him."

BIDEN ADMIN ANNOUNCES NEW BORDER PATROL CHIEF TO REPLACE RAUL ORTIZ

John Tien at Mt Vernon

Deputy Secretary of Homeland Security John Tien delivers remarks at a naturalization ceremony at George Washington's Mount Vernon estate in Virginia. (Kevin Dietsch/Getty Images)

"Indeed, we have co-led the Department through two amazing, busy and important years safeguarding our Nation. ‘S1’ is a great and gracious leader. We are lucky to have him as Secretary. I am even more lucky to call him my friend."

He said he would most fondly remember the moves to improve pay, training facilities and technology support for employees.

In a statement, Mayorkas praised Tien as "an extraordinary patriot and public servant and a wonderful human being." 

"For the past two years, Deputy Secretary Tien has led transformational initiatives. He coordinated interagency efforts in support of international pre-screening operations in Operation Allies Refuge; led interagency policy development in Operation Allies Welcome; created innovative programs to disrupt and dismantle international criminal organizations involved in fentanyl and human smuggling; led the development of our Department’s strategy in the Indo-Pacific Region; and much more," he said.

He also cited Tien’s work at G7 ministerial meetings and internal efforts to strengthen training, hiring and improve facilities.

ICE ACTING DIRECTOR TO RETIRE AT END OF JUNE, SECOND MAJOR BORDER SECURITY-RELATED RETIREMENT IN A WEEK 

Mayorkas testifies

Homeland Security Secretary Alejandro Mayorkas testifies before a House Appropriations Subcommittee on April 27, 2022, in Washington, D.C.  (Kevin Dietsch/Getty Images)

Tien’s announcement is the latest in a number of high-profile departures for the agency. In May, Border Patrol Chief Raul Ortiz announced he would be retiring at the end of this month. 

Earlier this month, acting Immigration and Customs Enforcement Director Tae Johnson announced he will be stepping down at the end of this month.

Last year, then-Customs and Border Protection Director Chris Magnus quit the agency after being told he would be fired if he did not resign.

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The latest departures come after what the administration has hailed as a successful implementation of a strategy to deal with the end of the Title 42 public health order at the beginning of May.

While numbers spiked to historic levels, with over 10,000 daily migrant encounters leading up to the end of the expulsion order, the administration says numbers have dropped by approximately 70% since then – although officials have cautioned about concluding that numbers will remain relatively low.