The U.S. military's top officer says he believes the situation in Afghanistan is "serious and deteriorating."

The chairman of the Joint Chiefs of Staff, Admiral Mike Mullen, said in an interview on U.S. television CNN's State of the Union Sunday that the Taliban insurgency has "gotten better [and] more sophisticated" in its tactics over the past couple of years.

In a separate interview on NBC's Meet the Press, Mullen said the U.S. military is focused on preventing another terrorist attack on U.S. soil and that its current strategy in Afghanistan is intended to disrupt and defeat al-Qaida, the Taliban and its extremist allies.

The Obama administration is expecting an assessment from its commander in Afghanistan, General Stanley McChrystal, in the next two weeks on the current situation there.

Republican Senator John McCain said in an interview on ABC's This Week Sunday that McChrystal's assessment should say exactly how many troops are needed in Afghanistan.

But Mullen said the upcoming assessment will not detail what resources are needed in Afghanistan.  He also would not speculate whether more troops are required there.

Both Mullen and McCain said they expect to have a better idea on what, if any, progress is being made in Afghanistan within the next year to year-and-a-half.(file)