LEADERS of the two principal contending nations on the Indian subcontinent fittingly have taken an important step toward reducing tension. Indian Prime Minister Rajiv Gandhi and Pakistani President Muhammad Zia ul-Haq have agreed not to attack each other's nuclear facilities, a prospect that had been of growing concern to other nations. And they promised to redouble efforts to solve several major disputes between their two countries, from border claims to economic matters. In recent months tensions had appeared to be rising again between the two countries, which have fought three wars since their mutual independence in 1947 from Britain. It is to the credit both of Gandhi and Zia that they have moved to defuse the situation. Their success thus far shows how helpful it can be for leaders of opposing nations to have a base of frequent contacts on which to build: This is the sixth meeting between the two since Gandhi assumed the leadership of India nearly 14 months ago .
The meetings are in keeping with the activist role that Prime Minister Gandhi has taken, with considerable success, in approaching his nation's most urgent problems. He has gone to Washington in an effort to warm previously chilly US-India relations; has sought through vigorous diplomatic leadership to bring about peace between warring factions in Sri Lanka, the island nation off India's southeastern coast; and has endeavored to smooth Delhi's troubled relations with India's rebellious Sikhs.
One of the historic challenges to Indian leaders remains: Strengthening popular support for the Delhi government in areas where factional pulls are strong. In Assam last week local elections dealt Gandhi and his Congress Party a sizable defeat; the prime minister's party earlier lost similar contests in the Punjab.
All problems between the India and Pakistan are far from solved; indeed, many of the thorniest ones remain to be grappled with. Reaching solutions will test both governments' commitment to better relations and staying power.
Yet a good start has been made. Gandhi called last week's get-together a ``first step toward establishing confidence in each other'' -- an indispensable element in the settling of international disputes.