FACTBOX - U.S. Navy ships prepared for Japan earthquake relief

Whirlpools are seen following a tsunami and earthquake in Iwaki city, Fukushima Prefecture, March 11, 2011.

REUTERS - President Barack Obama offered U.S. ally Japan any assistance needed on Friday after a massive earthquake and tsunami devastated coastal areas and killed hundreds of people.

Here is a list of U.S. Navy vessels being positioned for earthquake and tsunami relief, according to the Pentagon.

USS ESSEX, (an amphibious assault vessel -- complement: 1,200 (Navy) 1,800 (Marines) with the embarked 31st Marine Expeditionary Unit, arrived in Kota Kinabalu, Malaysia, this morning. The ship is making preparations to depart as early as Friday evening.

USS BLUE RIDGE (command and control ship -- complement: approximately 1,500 all Navy), which arrived in Singapore this morning, is loading a Humanitarian Assistance/Disaster Relief kit and making preparations to depart Saturday morning.

The USS BOXER Amphibious Ready Group, which includes:

* USS BOXER (amphibious assault ship complement: 1,174 Navy, 2,070 Marines).

* USS GREEN BAY (amphibious transport dock - complement: approximately 360 crew -- can deliver a force of approximately 800 Marines).

* USS COMSTOCK (amphibious dock landing ship - complement: approximately 347 Navy crew and approximately 400 Marines), is currently at sea in the Western Pacific en route to a scheduled replenishment in Guam.

The USS RONALD REAGAN carrier strike group is now at sea in the Western Pacific en route to a scheduled port visit to South Korea, but is postured to respond if directed. The RONALD REAGAN is a nuclear-powered carrier with 3,200 Navy crew and 2,480 aviators and air wing personnel, and approximately 85 planes.

The USS TORTUGA, (dock landing ship -- complement: approximately 410 Navy crew and 400 Marines) currently in Sasebo, Japan, is making preparations to get underway as early as Friday evening.

The landing ships USS HARPER'S FERRY and USS GERMANTOWN were in the Pacific and have been redirected to Japan.

The aircraft carrier USS GEORGE WASHINGTON is in maintenance and docked in Yokosuka, Japan.

(Editing by Xavier Briand)