Washington (CNN) The US Marine Corps' stealth F-35B Lightning fighter jet could fly its first combat mission within days, according to several US defense officials, who told CNN that the fifth-generation aircraft are currently aboard the USS Essex amphibious assault ship and should soon be in a position to conduct airstrikes over Afghanistan.

The USS Essex has already sailed from the Gulf of Aden into the North Arabian Sea and is expected to move into the Persian Gulf in coming days, one official said.

F-35 pilots have been conducting intelligence and surveillance missions in Somalia while on standby to conduct air support for US troops on the ground there if needed.

While available for support, the advanced fighter jet was not used in an airstrike over Somalia on Saturday that killed 18 militants after US and local forces came under attack.

In May, Israel Defense Forces said they were using their version of the F-35 in operational missions, striking at least two unspecified targets in the region.

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