WASHINGTON (AP) — President Barack Obama nominated the U.S. Coast Guard's second-in-command on Tuesday to run the Transportation Security Administration, tasking Vice Adm. Peter Neffenger with keeping passengers safe amid increasingly complex threats from the Middle East and beyond.

Neffenger, who has served as the Coast Guard's vice commandant since 2014, has served in the Coast Guard since 1981 and once oversaw port security in Los Angeles and elsewhere in California. He also was the deputy incident commander for the oil spill that resulted from the 2010 Deepwater Horizon oil rig explosion.

If confirmed by the Senate, he'll replace former TSA chief John Pistole, who announced his retirement last year after 4 ½ turbulent years leading the agency best known for its role screening passengers at U.S. airports. With a workforce of more than 60,000 employees, the TSA runs security operations at more than 450 airports.

Obama described Neffenger as a "recognized leader" who had taken on the nation's critical challenges in the past. "The talent and expertise Vice Adm. Neffenger brings to his new role after more than three decades at the U.S. Coast Guard will be valuable to this administration's efforts to strengthen transportation security," the president said in a statement.

Neffenger's nomination comes as the agency struggles to address evolving threats that have become even harder to detect since the TSA was created in the wake of the Sept. 11, 2001 terrorist attacks. Under Pistole, the TSA began looking at how to beef up security without infringing on commerce, trade and tourism.

U.S. intelligence officials have warned that extremists from the Khorasan Group, al al-Qaida-linked group in Syria, have schemed with bomb-makers from al-Qaida's Yemen affiliate to find new ways to get explosives onto planes without detection. Last year the TSA asked for additional screening measures at certain overseas airports, such as requiring passengers to turn on laptops, tablets and other electronic devices.

Sen. Kelly Ayotte, R-N.H., who sits on the Senate's Homeland Security and Governmental Affairs, welcomed the nomination and said the TSA needs "strong leadership and a coherent strategy" to ensure the best security for the U.S.

"Filling this vacancy is a critical and long overdue step in that process," Ayotte said.

Pistole, who now serves as president of Anderson University, drew consternation from airlines and lawmakers when he announced plans to allow passengers to carry small knives, bats and other previously prohibited items with them onto flights. Pistole eventually had to withdraw that proposal.

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