A US Navy warship believed to be carrying thousands of Marines and sailors to the Middle East is nearing the Malacca Strait off Singapore as it makes its way to the region, maritime tracking data showed Tuesday.

The amphibious assault ship USS Tripoli was approaching Singapore, at the southwestern edge of the South China Sea, Tuesday morning, according to AIS tracking data seen by CNN.

US Navy ships often move with AIS transponders turned off. Revealing their positions while transiting areas with heavy maritime traffic, like the waters around Singapore, enables safer operations.

The Tripoli is believed to be carrying troops from the Okinawa-based 31st Marine Expeditionary Unit (MEU), a rapid-response force of 2,200 personnel, after the Pentagon ordered the unit to deploy, according to three officials familiar with the plans.

CNN has asked the US Navy’s 7th Fleet and 5th Fleet for comment.

Officials told CNN the unit was being sent to the Middle East, without revealing exactly where it would be deployed or what it would be used for.

An MEU consists of four elements: command, ground combat, air combat and logistics combat. MEUs typically have been used for missions like evacuations and amphibious operations that require ship-to-shore movements, like raids and assaults. They also have ground and aviation combat components, and some units are trained for special operations.

Marinetraffic.com showed a track for an “unspecified US warship” departing Okinawa on March 11, through the South China Sea and nearing Singapore Tuesday morning at a speed of about 22 mph.

Based in Sasebo, Japan, the Tripoli, almost 850 feet long and displacing 45,000 tons, is essentially a small aircraft carrier an d carries F-35 stealth fighters and MV-22 Osprey transports as well as landing craft to move troops ashore.

It is the lead ship in an amphibious ready group, which would normally include the amphibious transport docks USS New Orleans and USS San Diego. CNN could not confirm the presence of those smaller ships with the Tripoli in maritime tracking sites Tuesday. (CNN)

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