CAMBRIDGE, Mass. — The terrorist assault in Mumbai targeted not only India's economy and sense of security, but also the India-Pakistan detente that has taken shape since 2004.

The attackers did not hide their faces or blow themselves up with suicide jackets. Anonymity was not their goal. They wanted to be identified as defenders of a cause.

Unless this cause is fully understood, and its roots revealed across the region, this attack may prove to be the beginning of the unmaking of South Asia.