Mary, what you complain to have been missed has actually been done. The USA had the information about a possible tsunami early and did inform the US embassies in several countries hit later. The embassies did try to phone local services responsible for giving warnings. But due to the holiday season, to the (locally) very early time of the day and to the inefficiency of the local institutions no warnings reached the people that could have profited from hearing them.

The blame here rests with the local authorities and with nobody else.

Wolfgang