Washington ? Though the Soviet Union is gone, the nuclear fears that fueled the Cold War haven’t disappeared. Most Americans think nuclear weapons are so dangerous that no country should have them, and a majority believe it’s likely that terrorists or a nation will use them within five years.

The Bush administration repeatedly warns about nuclear weapons and is using diplomacy — and force — to try to limit the threat.

Still, North Korea claims it has nuclear weapons now and is making more. Iran is widely believed to be within five years of developing such weapons. And security for the nuclear material scattered across the countries of the old Soviet Union remains a major concern.

Lurking in the background is the threat that worries U.S. officials the most — terrorists’ desire to acquire nuclear weapons.

All that helps explain why 52 percent of Americans think a nuclear attack by one country against another is somewhat or very likely by 2010, according to an AP-Ipsos poll. Fifty-three percent think a nuclear attack by terrorists is at least somewhat likely.

Two-thirds of Americans say no nation should have nuclear weapons, including the United States, and most of the others say no more countries should get them.

About one-third of those in an ABC News-Washington Post poll in the mid-1980s — when the Cold War was hot — thought there would be a nuclear war in the next few years between the two superpowers.

Six in 10 Americans 65 and older approve of the use of the atomic bomb at the end of World War II, while six in 10 from ages 18 to 29 disapprove.

Overall, 47 percent of those surveyed approved of dropping the bombs on Hiroshima and Nagasaki while 46 percent disapproved, according to the poll of 1,000 conducted by Ipsos-Public Affairs from March 21-23 with a margin of sampling error of plus or minus 3 percentage points.

The United States, Britain, Russia, France and China have nuclear weapons, and Pakistan and India have also conducted nuclear tests. Many believe Israel has nuclear weapons, but that country has never acknowledged it. North Korea claimed in February that it had nuclear weapons.