NEW DELHI, India ? Nuclear rivals India and Pakistan exchanged fire across their border in Kashmir on Monday, and the Indian military reportedly took control of the country’s paramilitary forces and merchant marine in a sign of building tension over the disputed Himalayan region.

Each side in the simmering conflict sought to bring international pressure to bear on the other. India said it asked foreign help in isolating Pakistan, which requested international assistance in starting talks to settle the territorial dispute.

Indian Army soldiers clean their rifles at a camp in Punjab, India, near the international border with Pakistan. The two nations stand on the brink of a military conflict, with about 1 million soldiers deployed along the frontier.

In Washington, the Bush administration announced plans to send Deputy Secretary of State Richard Armitage to the region. State Department spokesman Richard Boucher said the administration was “strongly concerned” about the situation.

India has refused to negotiate until Pakistan stops its alleged support for Islamic militants who have launched attacks on the Indian side of the border in Kashmir. Pakistan denies backing the militants but does support the goal of separating the Indian portion of mainly Muslim Kashmir from Hindu India.

The two nations have sent about 1 million soldiers to their frontier as the dispute flared anew about Kashmir, which has provoked two of the wars the countries fought since independence from Britain in 1947.

U.N. Secretary-General Kofi Annan called on both sides “to exercise maximum restraint to avert a further escalation of tensions,” U.N. spokesman Fred Eckhard said in New York.

He said Annan also was “very concerned” at the high level of casualties due to persistent firing alone the Line of Control, the 1972 cease-fire line that divides Kashmir.

The Press Trust of India news agency reported India’s powerful interior minister, Lal Krishna Advani, said the army had been asked to consult a top secret set of directions from the government about offensive operations, known as the War Book.

The day-to-day records of past wars and battle plans is so secret that it is handed personally by the civilian authority to the military authority, and is consulted only when the army is asked to prepare for war, a senior army officer told The Associated Press on condition of anonymity.

Press Trust of India quoted Advani as saying the decision to put paramilitary troops and the merchant navy under the military command was “an indication that we are moving in a certain direction.”