The two sailors went missing Thursday evening, US Central Command said in a brief statement.

"Search and rescue operations are currently ongoing to locate the two sailors. For operational security purposes, we will not release additional information until the personnel recovery operation is complete," it said.

The sailors were "forward-deployed" to the US 5th Fleet area of operations "supporting a wide variety of missions."

The 5th Fleet's area of operations covers about 2.5 million square miles of water and includes The Gulf, Red Sea, Gulf of Oman and parts of the Indian Ocean, according to the military's website.

US forces have long operated in Somalia in coordination with and on behalf of the government, mostly conducting regular aerial strikes to support official forces fighting extremist Al-Shabaab rebels.

Washington has designated Al-Shabaab as a terrorist organization.

According to the US Africa Command, Al-Shabaab is "the largest and most kinetically active Al-Qaeda network in the world and has proved both its will and capability to attack US forces and threaten US security interests."