Clinton Keeping Up Pressure on N. Korea : Nuclear arms: He says Pyongyang could be the top security threat if it withdraws from treaty.

President Clinton warned Friday that North Korea, said by sources to possess one or two nuclear weapons, could become the United States’ biggest national security “nightmare” if it carries out its threat to withdraw from the Nuclear Non-Proliferation Treaty.

The President, who will visit South Korea July 10 and 11 after the economic summit of industrial nations in Tokyo, said that he is doing all he can to pressure the North Koreans to remain committed to the treaty. The United States cannot afford to let the Communist country build a nuclear arsenal, he said, and needs to be “extremely tough about it.”

The North Koreans originally planned to withdraw from the 153-nation treaty on June 12 but suspended the move under pressure from the United States. Clinton said at the time, however, that the effort was only a first step “toward ensuring North Korean participation in a strong international non-proliferation regime.”

Clinton made his remarks in a luncheon interview with about a dozen journalists in a White House dining room, where he also answered questions on a variety of other subjects, including what he described as a “negative frame of mind” prevailing in all seven of the economic summit nations--the United States, Canada, England, France, Germany, Italy and Japan.

All of the countries are in the midst of economic decline and most have been undergoing political upheaval, leading to what Clinton called “the doldrums, a historic phenomenon.” At the two-day Tokyo meeting, which begins Wednesday, three steps should be taken, he said, to address the malaise: Promoting an open trade policy, coordinating economic policy among the nations and studying “the disconnect between economic growth and jobs” as illustrated in France, where unemployment remains high, despite strong economic growth.

On the subject of security, Clinton said that, while the biggest immediate problems for the United States involve Iran, Iraq, terrorism and nuclear proliferation, North Korea could become the “bigger nightmare” because of the country’s potential for building nuclear weapons that would threaten Japan and China.

For that reason, he said, the United States will do everything it can to dissuade North Korea from withdrawing from the treaty.

American officials are concerned not only that North Korea’s withdrawal might touch off a nuclear arms race but that it would inspire Iran to follow suit. The officials consider North Korea, Iran and Iraq to be at the heart of the proliferation problem. Already the three nations are considered major threats because they are either producing or buying mid-range ballistic missiles and working on chemical and bacteriological weapons.

The President also said that he plans to reassure the South Koreans that the United States will stand firm in its long-term commitment to maintaining a “very strong presence” in their country, regardless of the state of the American economy or U.S. defense cutbacks.

The luncheon, billed as a pre-summit briefing, was hurriedly assembled through telephone invitations delivered Thursday. Vice President Al Gore and half a dozen top White House aides, including David Gergen, also attended and chatted with journalists as part of Gergen’s effort to dispel what he called the “poisonous relations” that existed between the press and the White House when he joined Clinton’s staff on May 29.

Clinton expressed little concern about reports that European leaders question his credibility as a major world leader. Although his own anemic poll numbers, which show an approval rate near 40%, are higher than those of any of the embattled European leaders, he said that he would be surprised if there were not leadership questions raised about him. He attributed those concerns to three things: Problems in Europe, where people are “psychologically down”; his brief tenure in the White House, and the difficulty he has had in persuading European leaders to join him in intervening decisively in the war in Bosnia.