North Korea and Iran have repeatedly given every evidence that they are going forward with plans to produce nuclear weapons despite pressure and cajoling from Europe and America not to do so.

Consequently, a new nuclear era is at hand as other nations will likely be spurred by North Korea and Iran to go nuclear themselves.

Said a retired U.S. military officer with experience in nuclear weapons: "We need to start thinking about how we will live in a world where nonproliferation has failed."

That will require a new doctrine to deter nuclear hostilities so awful that, as former Secretary of Defense Harold Brown once wrote, "The living would envy the dead." The doctrine of mutual assured destruction, or MAD, that kept the United States and the Soviet Union from waging nuclear war will no longer do.

Amid this gloom are rays of light. Several nations, including Argentina, Brazil and South Africa, have given up nuclear arms. Mongolia and Japan have forsworn them. Proposals for nuclear-free zones in Northeast Asia, Southeast Asia and the Pacific struggle for life.

Mongolia has declared itself to be nuclear-free and persuaded its nuclear neighbors, China and Russia, to agree to respect that. This demonstrates, said Mongolia's former ambassador to the United Nations, Enkhsaikhan Jargalsaikhan, "that each state can make its unique contribution to nonproliferation."

Even though many Japanese perceive nuclear threats from China and North Korea, the government of Prime Minister Junichiro Koizumi has stuck to a longstanding policy of abstaining from nuclear arms. Japanese strategists say that policy will continue so long as the U.S. deterrent protecting Japan remains credible.

From North Korea, the latest sign of its intent was carried by the Korean Central News Agency: "Under the present situation it is illogical to discuss with the U.S., the assailant, the issue of dismantling the nuclear deterrent built up by the DPRK for self-defense." (Democratic People's Republic of Korea is the nation's formal name.)

In Tehran, a government spokesman, Gholam Hossein Elham, told correspondents that "Iran will today resume nuclear fuel research as scheduled," defying pleas from Europe and America to postpone that decision. "Very, very disastrous signals," said the German foreign minister, Frank-Walter Steinmeier. The White House echoed that.

Elsewhere in Asia and the Middle East, nations that might develop nuclear arms include South Korea, Taiwan, Vietnam, Thailand, Malaysia, Indonesia, Myanmar, Bangladesh, Saudi Arabia, Syria and Egypt.

India and Pakistan are already declared nuclear powers, while Israel's nuclear arsenal is an open secret. The other five are the United States, Russia, Britain, France and China.

Deterring North Korea or Iran would be far different from the MAD standoff at the depth of the Cold War. The United States and the Soviet Union deterred each other with massive nuclear arsenals that made devastating retaliation a certain response to nuclear attack.

Today, North Korea and Iran, with their relatively puny stocks of nuclear weapons, cannot attack the United States with sufficient force to prevent a retaliatory strike. Therefore, some American strategic thinkers argue, negotiations with North Korea and Iran, with their empty warnings of serious consequences, are futile and should cease.

"Blustering does not become a superpower," says a U.S. military officer. "We have gone from speaking softly while carrying a big stick to blustering constantly while carrying no stick at all."

Instead of bluster, Pyongyang and Teheran would be told, diplomatically in public and forcefully in private, that a nuclear threat to the United States, its deployed forces and its allies would draw a withering response at a time, place, and means of U.S. choosing. Also advocated are sanctions but not military invasion.

Deterring terrorists who acquire nuclear bombs would be harder because finding a clearly defined target would be difficult. Terrorists could obtain nuclear bombs by stealing them from Russia, where safeguards have become lax, or by making several themselves as the technology becomes more available by the day.

Terrorists could bring those weapons into the United States, says a study by the Congressional Research Service: "Terrorists might smuggle a weapon across lightly guarded stretches of borders, ship it in using a cargo container, place it in a crude-oil tanker, or bring it in using a truck, a boat or a small airplane."

In response, the research service says, the U.S. relies on a "layered defense." The layers include helping the Russians to control access to their nuclear arsenal, safeguarding all enriched-uranium sources, inspecting ship containers and enforcing greater U.S. border security.

At best, however, that layered defense is leaky.

Honolulu-based Richard Halloran is a former New York Times reporter in Asia. He wrote this article for The Advertiser.