"Our hearts go out to our friends in Japan and across the region, and we're going to stand with them as they recover and rebuild from this tragedy," Obama said during a White House news conference.
Hundreds were dead or missing in Japan following Friday's 8.9 magnitude earthquake — the largest in Japan's history — and the accompanying tsunami. The West Coast and several islands in the Pacific were also under tsunami warnings, through no major damage was reported in the U.S. as the first waves swamped Hawaii's beaches and grazed the coastline of the mainland.
Obama said he was confident that Japan would successfully rebound from the potentially "catastrophic" disaster, and offered his condolences to the families of those who were killed.
"When you see what's happening in Japan, you are reminded that for all our differences in culture or language or religion, that ultimately humanity is one," Obama said.
Obama spoke with Japanese Prime Minister Naoto Kan earlier Friday, and said the Japanese leader told him there were no radiation leaks from Japan's nuclear power plants. The Japanese government ordered thousands of residents near a plant in the city of Onahama to move back at least two miles from the plant. The reactor was not leaking radiation but its core remained hot even after a shutdown.
One U.S. aircraft carrier is already in Japan, and a second is on its way to assist with the recovery efforts. A U.S. ship was also heading to the Marianas Islands.
With West Coast residents anxiously watching tsunami warnings in their area, Obama offered his assurances that his administration was taking the threat seriously and monitoring the situation closely. He urged residents in the affected areas to take warnings from local officials seriously and evacuate if told to do so.
The military was preparing to offer aid to Hawaii and the West Coast, if needed. The Coast Guard said cutter and aircraft crews were positioning themselves in the area to be ready to conduct response and survey missions as soon as conditions allow.
Obama's chief of staff Bill Daley notified the president about the earthquake in Japan at 4 a.m. Washington time. Obama activated the Federal Emergency Management Agency, and huddled with senior advisers at the White House to discuss plans to assist Japan, as well as the U.S. states and territories that could be affected.
Pentagon spokesman Col. David Lapan said U.S. and Japanese officials are talking constantly to determine what is needed, but it could include food, water, shelter, and medical supplies. The ships also have medical facilities to treat injured
The State Department said no Americans killed or injured in Japan; there were also no reports of damage to U.S. installations or ships in the area. The department issued a travel alert, strongly urging U.S. citizens to avoid non-essential travel to Japan.
"Tokyo airports are currently closed," it said. "Other airports in Japan may be closed or have restricted access. Public transportation, including trains and subways, are closed in the Tokyo area, and service has been interrupted in many other areas."
"Strong aftershocks are likely for weeks," the department said. It urged U.S. citizens currently in Japan to "contact family and friends in the United States to confirm their well-being at the earliest opportunity."
Spokesman P.J. Crowley tweeted early Friday that ambassador John Roos "has moved our U.S. Embassy's command center to an alternate location as a precaution, given the many aftershocks in Tokyo."
"We have been watching a hopeful tsunami sweep across the Middle East. Now we are seeing a tsunami of a different kind sweep across Japan," Crowley said.
At home, FEMA Administrator Craig Fugate said that "our immediate priority is the safety of the people and communities in the affected areas."
"FEMA is closely monitoring the affects of the earthquake and subsequent tsunami that struck Japan," he said, "and through our regional offices in the West Coast and the Pacific area, we are in close contact and coordination with state and local officials and stand ready to support them in any way needed."
Vice President Joe Biden, making a joint appearance at a news conference in Chisinau, Moldova Friday with Prime Minister Vlad Filat, said "the thoughts and prayers of the American people" are with the Japanese, who he said had suffered through a "mega earthquake."
"We, the United States, stand ready to do anything we can to help our Japanese friends as they deal with the aftermath of this tragedy," Biden said.
___ Associated Press reporters Matthew Lee, Alicia Caldwell, Lolita Baldor and Bradley Klapper contributed to this story.
Copyright 2011 The Associated Press.