FOR Robert Gates, the hard part is just beginning.After his rocky confir-mation hearings to head the Central Intelligence Agency, no doubt Mr. Gates and his supporters, including President Bush, sighed in relief when the Senate ultimately approved the nomination. But now the new director of central intelligence must roll up his sleeves and get to work. Gates has to lead the CIA and the rest of the United States intelligence community in directions that not only are new for it but also depart from his own background as a career intelligence officer. A man who came up as a Soviet specialist during the cold war, Gates must redefine the intelligence agencies' missions and priorities for the post-cold-war era. He will have to be his first, and most apt, pupil. Some say that with the threat of a superpower confrontation gone the US can demobilize much of its spy apparatus. Ironically, though, in the new world order American intelligence likely will have a wider range of responsibilities, and will require a broader array of capabilities and resources, than at any time since the CIA was founded in 1947. Nonetheless, the federal deficit will prompt cuts in the intelligence budget in the years ahead. Gates will have to do more with less. His management mettle will be tested to the utmost. Among its jobs, the CIA, together with its sister agencies in the military branches, must: * Monitor the proliferation of weapons of mass destruction around the world. Soviet territory is still bristling with nuclear missiles that must be accounted for. And the intelligence agencies must inventory the growing arsenals of nuclear, chemical, and biological weapons in other, perhaps less predictable hands. * Keep an eye on regional conflicts around the globe that could challenge US interests. * Track terrorist networks and narcotic traffickers. * At a time when power is increasingly measured in terms of economic prowess instead of armaments, analyze threats to America's commercial, financial, and trade interests. In this realm of competition, even allies are potential adversaries. As he recasts the intelligence community's goals, Gates will also have to retool its machinery. This will entail a fresh look at such matters as the balance between the spy agencies' operational and analytical divisions and the blend of human and high-tech information-gatherers. The CIA should also try, through better incentives and less bureaucratic hedging, to improve its forecasting skills. The agency was formed, after all, to prevent another Pearl Harbor, not just count Japanese aircraft carriers.