Defense Secretary Donald Rumsfeld says the United States is keeping a close eye on the tense standoff between India and Pakistan.

Mr. Rumsfeld calls it a difficult and tense situation and says President Bush and other senior U.S. officials are engaged in diplomatic efforts to ease the crisis.

The defense secretary says so far there has been no impact on the U.S.-led anti-terrorist operation in Afghanistan. But he voices concern that if the situation worsens, Pakistan might re-deploy troops currently hunting down Taleban and al-Qaida fugitives along the Afghan border.

"They have not yet moved forces from the Afghan border, and that is very encouraging to us, because it would be a big disappointment to us, needless to say, because they are performing an important task," said Mr. Rumsfeld. "They must have seven or eight, nine battalions along the Pakistan-Afghan border, which is clearly a deterrent to people trying to come across, trying to escape from Afghanistan."

Mr. Rumsfeld says another potential problem if the situation worsens is that the United States could lose overflight rights in Pakistan. He adds that basing arrangements for U.S. personnel could also be affected.

"That would be difficult for us, and unfortunate," Mr. Rumsfeld went on to say. "Needless to say, we've got thousands of Americans, military as well as civilian, in Pakistan, and clearly the bases where many of the military people are located would conceivably be - require different force protection arrangements."

Mr. Rumsfeld stressed that the United States has expressed its concerns to India and Pakistan with what he characterizes as care and clarity. In the meantime, he said U.S. officials continue to monitor developments closely.