The US military has a very large presence on the Japanese island of Okinawa- and according to the department of defence, Japan has now officially asked the US for assistance.
The following ships are being prepared to deploy:
The USS Tortuga (amphibious craft) - in Japan, leaving for disaster zone tonight.
The USS Essex (larger amphibious ship) carryign 31st Marine Expeditionary Unit - in Malaysia - leaving tonight.
The USS Blue Ridge (Command and Control Ship) Singapore - on way to disaster zone tomorrow morning.
The USS Ronald Reagan Carrier Strike Group - currently in the Western Pacific - is on its way now. It can transport aid with helicopters - and has water desalination and medical facilities.
US defence secretary Robert Gates:
I've been kept informed all day long about the tsunami in Japan, the earthquake and tsunami. As best we can tell, all of our people are OK, our ships and military facilities are all in pretty good shape. We obviously have huge sympathy for the people of Japan and we are prepared to help them in any way we possibly can. It's obviously a very sophisticated country, but this is a huge disaster and we will do all, anything we are asked to do to help out.
Ritsuko Allen, is a 40-year-old resident of Aioi in Hyogo, southwest Japan, and spoke to Al Jazeera's D.Parvaz.
She said she didn't feel the earthquake today, but when she finally managed to reach her family hours later, she was relieved to hear that the family home was only "messed up" by the quake.
Allen lived in Tokyo in 1995, when the Kobe earthquake hit, and thought to herself today: "It if hit Tokyo, (it'll) be done. No way to survive."
She said she knows people in Sendai and doesn't know if they're alive. She said that local reports say that 300 have died and 530 are missing.
"I dont know they are ok or not. I pray for them," said Allen, who added she's in shock with "so many people gone ... in the sea."
AFP news agency is quoting Japan's trade minister as saying "a small radiation leak could occur" at Fukushima nuclear plant - after officials said a pressure build-up had occurred in one of the power station's reactors.
Attorney Clint Conner, husband of Christine (interviewed earlier), works in the Marunouchi area near the busy Tokyo station, a business district with lots of tall buildings. He spoke to Al Jazeera's D.Parvaz.
He said that having lived in northern California, he'd experienced quakes before, "but never really felt them" - he said he notices or feels an earthquake about every two or three weeks in Tokyo.
"I was in a conference room preparing for a meeting," said Conner.
It didn’t take long to realise this was bigger than anything I had felt before and was prepared to feel. My mind quickly went from preparing for the meeting to getting out of the building and my family. Going down the stairwell was frightening. I could feel the guy behind me pressing me. I thought the stairwell would collapse inward. I missed the handle to the door leading to the lobby because the building was shaking so hard.... I really felt like the building was going to come down. It was loud and the shaking was violent.
He said that it took about 20 minutes for everyone to evacuate the building, and that "the scene outside was amazing", with people crying, in shock.
Tall buildings were swaying like palm trees – their window dressings smacking the windows and lights swaying wildly. There is a building under construction across from mine with cranes on the roof. The cranes were clanking against each other and making an awful sound. It seemed they would fall any minute.
With transportation systems down, Conner had to walk home to the Roppongi district.
I walked home with a mass of humanity. This is a city of 18million in tight quarters. You can imagine how many people were walking on the streets, considering no one wanted to be inside buildings, and the trains were not running.
He said that people were "fairly calm" once it became clear that buildings would not collapse.
Conner is very impressed at how the authorities have handled things.
My deepest respect goes out to the Japanese government, city planners, architects, and construction workers for doing a mind-blowing job of building a city ... We just experienced the fifth largest earthquake on record - the largest ever recorded in Japan's history - but the city remains relatively safe and the utilities are working.
Japanese media in Tokyo are reporting 300 dead, 722 injured and 537 missing, Hyogo resident Ritsuko Allen tells Al Jazeera.
Liquefaction is happening at the Tokyo Disneyland parking lot ... many school, university and government buildings are open for people who cannot go home in Tokyo.
Liquefaction is the process by which sand and water normally trapped several metres underground bubbles to the surface.
Buildings burn in Yamada town, Iwate Prefecture in north-east Japan, following the earthquake.