London: The US air force delivered emergency coolant to an earthquake-hit nuclear power station in Japan on Friday but initial world reaction to the massive tremor and tsunami was otherwise marked by stunned inaction.
"The world is shocked and saddened by the images coming out of Japan this morning," UN Secretary-General Ban Ki-moon said.
"We will do anything and everything we can."
But as leaders across the globe reacted and the tsunami wave roared across the Pacific, damaged airports in Japan and uncertainty about the level of assistance required by a wealthy nation well used to earthquakes meant there was little immediate move to bring in resources from outside.
Among instant, critical help was the delivery of coolant to a damaged nuclear plant. US Secretary of State Hillary Clinton said the US air force based in Japan had transported it.
President Barack Obama, whose own country's Pacific coasts were braced for a surge of waves from the quake, said: "The United States stands ready to help the Japanese people in this time of great trial ... The friendship and alliance between our two nations is unshakeable, and only strengthens our resolve to stand with the people of Japan as they overcome this tragedy."
The US Defence Department was preparing American forces in the Pacific to provide relief.
Another neighbour across the sea, Russian President Dmitry Medvedev, said: "Russia is ready to offer Japan all possible aid to cope with the aftermath of this tragedy."
The Russian emergency services agency ERMACOM offered 40 people with three sniffer dogs, while Singapore had civil defence forces on standby and Poland offered firefighters.
China, Switzerland and the United States also offered rescue teams, while Britain, France and others said they were ready to offer whatever help was required.
South Korea said it had 40 emergency rescue workers on standby to fly to Japan, pending clearance.
Chinese Premier Wen Jiabao said Beijing was ready to provide Japan with any assistance it required.
In Europe, British Prime Minister David Cameron said: "We've had a terrible reminder of the destructive power of nature, and everyone should be thinking of that country and their people, and I've asked immediately that our government should look at what we can do to help."
Foreign Minister William Hague said British rapid deployment teams were ready to travel immediately to the areas of most need.
French President Nicolas Sarkozy said: "France stands ready to respond to any requests from Japan for help in the face of this tragedy."
The senior officials of the European Union, Manuel Barroso and Herman van Rompuy, said in a statement: "We are deeply concerned at the news of the devastating earthquake which has struck Japan, causing a number of fatalities and serious material damage.”
"The European Union expresses its solidarity and condolences to the people and government of Japan, and to the families of the victims at this difficult time. We stand ready to assist in any way we can in case of need."
Japanese living or travelling abroad were glued to Internet screens and televisions, anxious for news of family and friends.
"I am very worried, I'm just sitting here watching television and reading news on the internet," said Kiriko Sato, 28, a seamstress living in Paris.
"In Sendai, there have been large tsunamis and many of my friends live there. Some of them cannot go home ... they came to work in the morning and they are unable to leave because there is no transport.”
"It is difficult to get in touch by phone but email is working well ... If I could I would go, but Narita (airport) is closed for now."
Poorer nations were at greater risk than Japan from the wall of water, though many have beefed up early warning systems and evacuation plans since the 2004 tsunami, the International Federation of Red Cross and Red Crescent Societies said.
"Our biggest concern is the Asia and Pacific region, where developing countries are far more vulnerable to this type of unfolding disaster. The tsunami is a major threat," spokesman Paul Conneally in Geneva earlier on Friday.
"At the moment, it is higher than some islands and could go right over them. That is a scenario that nobody wants to see."