NEW DELHI, India ? President Bush called the leaders of India and Pakistan on Wednesday as the United States geared up its diplomatic drive to prevent a war in one of the world’s most dangerous flashpoints.

Bush told Indian Prime Minister Atal Bihari Vajpayee and Pakistani President Gen. Pervez Musharraf “to take steps that will ease tensions in the region and reduce the risk of war,” said White House spokesman Ari Fleischer.

“The president reiterated to President Musharraf that the United States expects Pakistan to live up to the commitment to end all support for terrorism. The president emphasized to Prime Minister Vajpayee the need for India to respond with de-escalatory steps. To both leaders, the President stressed the need to choose the path of diplomacy,” Fleischer said.

India and Pakistan take entirely different positions on a key issue of the dispute whether Pakistan has stopped militants from infiltrating into the Indian-held side of the disputed territory of Kashmir to attack Indians and Kashmiris. India has said it will not hold talks until the infiltrations stop. Pakistan asserts that already has happened.

A war now would be the first since India and Pakistan acquired nuclear weapons. The two countries have fought three wars since they became independent in 1947.

Bush made the phone calls to the two leaders ahead of Deputy Secretary of State Richard Armitage’s scheduled meetings today with Musharraf in Islamabad and later with Vajpayee in New Delhi. Defense Secretary Donald Rumsfeld was following him within a few days. Their diplomacy followed efforts by the leaders of Russia, China, Britain and other countries to prevent a war.

The State Department on Wednesday issued new travel warnings to Americans in India and Pakistan, citing tensions at “serious levels.” The government warned Americans not to travel to India and Pakistan and strongly urged those already in the two countries to leave. There are about 60,000 Americans in India and several thousand in Pakistan.