The horrifying attacks on Mumbai serve to remind the world that political terrorism is relentless, indiscriminate and heartless. The mass violence employed by extremists, once confined to a few targeted nations such as Israel, has spread to every corner of the globe and continues to grow. This wasn't just about India and Pakistan, or Hindus and Muslims. It was about all of us.

Confronting this menace requires every nation to set aside old rivalries in order to overcome the greater evil. In this case, it is incumbent on both India and Pakistan — particularly the latter — to come to grips with the source of discontent. Both countries must work to put an end to the feud over the disputed land of Kashmir because that is a breeding ground for terrorism and a pretext for violence.

Blood and destruction are not new to this part of the world. The rioting and dislocation that followed the partition of 1947, when the independent nations of modern Pakistan and India were born, claimed about 500,000 lives. The legacy of this terrifying period has been decades of mutual hostility and repeated episodes of violence. Kashmir remains a divisive issue, a rallying cry for terrorists and a pretext for further bloodshed.

To their credit, both countries had been inching toward cooperation on several fronts in recent years. This is what the terrorists of Lashkar-e-Taiba, the chief suspects in this attack, intended to reverse by committing the massacre in Mumbai. The organization was created long ago by Pakistan's military as a subversive group in Kashmir, and even though Pakistan reportedly has severed all ties to it, India remains suspicious and rightly demands action from Pakistan.

This will require Pakistan to help eradicate all subversive movements in Kashmir. More important — and this extends beyond the menace to people of the subcontinent — Pakistan must take all necessary steps to clean up al-Qaida, the Taliban and other dangerous groups that operate inside Pakistani territory. This is the launching ground for attacks on U.S. and allied troops in Afghanistan, not to mention Pakistani civilians who have died in terrorist actions.

Prime Minister Asif Ali Zardari — whose late wife, Benazir Bhutto, was a victim of radical terrorism — appears to understand the threat that the so-called "nonstate actors" in Pakistan's hinterlands represent, not only to his own people but to the world.

He must persuade his military, the source of real power in Pakistan, that a failure to act, given the huge provocation in Mumbai, will mean falling into the trap set by militants who want to stoke a war with India. The United States should continue to counsel India that patience is the best option, but Pakistan must help its own cause with unstinting cooperation.