The U.S. military so far has not raised alert levels for its some 28,500 troops in South Korea following the death of North Korean leader Kim Jong-il or seen any alarming changes in the behaviour of the North's military, U.S. officials said on Monday.

South Korea, which put its forces on a higher alert level, said the North had test-fired a short-range missile prior to the announcement of Kim's death.

Martin Dempsey, chairman of the U.S. military's Joint Chiefs of Staff, said there was a likelihood the missile test was planned even before the death of Kim Jong-il, according to a Defence Department news service reporter travelling with him in Germany.

Another U.S. official, speaking to Reuters on condition of anonymity, also confirmed that view and several U.S. officials said the military had not heightened the alert level for American forces stationed in South Korea.

We have not seen any change in North Korean behaviour of a nature that would alarm us, Dempsey, the top U.S. military officer, was quoted as saying in Germany by American Forces Press.

North Korean state media hailed Kim's untested son as the Great Successor and Dempsey was said it was his expectation that Kim's son, Kim Jong-un will be the successor.

I would only say at this point that he is young to be put in this position and we will have to see if it, in fact, is him and how he reacts to the burden of governance that he hasn't had to deal with before, Dempsey was quoted as saying.

(Reporting By Phil Stewart; Editing by Bill Trott)