The rising tensions between Pakistan and India demand an energetic response from the United States. The successful campaign in Afghanistan must not give way to an ominous conflict between South Asia's two nuclear powers.
At heart, the problem is the same as in Afghanistan: religious fanaticism run amok. India is convinced that the terrorists who invaded its Parliament building Dec. 13 belong to Pakistan-based Islamic groups that operate in the disputed area of Kashmir.
India has demanded that Pakistan crack down on these groups and turn their leaders over to New Delhi for trial. For his part, Pakistan President Gen. Pervez Musharraf has arrested some militants and frozen their assets. The general's readiness to take on the extremists was shown by his support for US efforts in Afghanistan.
But India is far from satisfied. The current buildup of forces on the border, with reports of missiles being wheeled into place, suggests that military momentum could all too easily overtake diplomacy.
That won't resolve anything. Pakistan needs to continue reining in its extremists. India needs to contain its justifiable anger.
And the US must use its new friendship with both sides to help defuse an explosive situation.