As N. Korea’s nuclear program advances, US strategy is tested

SEOUL, South Korea — After years of trying to separate fact from propaganda about North Korea’s nuclear program, American and South Korean intelligence officials say they have concluded that the country can now mount a small nuclear warhead on short- and medium-range missiles capable of hitting much of Japan and South Korea.

The United States and its allies have sought for nearly a decade to prevent the North from gaining such capabilities, ever since it detonated its first atomic device a decade ago. Their failure is likely to raise new questions about the effectiveness of the policy toward North Korea, while ushering the long-simmering nuclear standoff with the North into a more perilous phase under its combative young leader, Kim Jong Un.

The assessment of the North’s new capabilities is not based on direct evidence from inside its nuclear program, senior officials said, but draws on intelligence gleaned from high-level defectors, analysis of propaganda images and data collected from North Korean missile and nuclear tests, which have accelerated over the past six months.

While some intelligence agencies suggested as early as 2013 that the North had learned enough about rocket engineering and the miniaturization of nuclear warheads to mount one on a shorter-range missile, there is a new consensus and greater confidence in that view in both Washington and Seoul, the officials said.

Given the years of research North Korea has devoted to the program, experts do not consider the conclusion particularly surprising. But the politics of the assessment, which means the North can target U.S. bases in South Korea and Japan, are delicate, both in the region and in the midst of a presidential election in the United States.

The Obama administration and the South Korean government are reluctant to discuss the North’s new capabilities publicly. Stung by the fiasco over the existence of unconventional weapons in Iraq 13 years ago, U.S. intelligence officials say they no longer advertise conclusions about other nations’ capabilities, and a senior South Korean government official who described the assessment to foreign reporters insisted on anonymity.

The officials said the public silence reflected an effort to avoid strengthening and encouraging Kim, who has doubled down on the nuclear program begun by his grandfather and father and has used it to tighten his grip on power. Publicly acknowledging the North’s advances would play into Kim’s narrative that only he can protect his nation, by defying its enemies and building a nuclear arsenal, the officials said.

Victor Cha, who was a senior official on President George W. Bush’s National Security Council, said U.S. policy had been “concerned about not overreacting to every North Korean provocation, and that made sense when their capabilities were not all that formidable.”

“But now they have been in a spiral of escalation,” he said, “and we are underreacting when their capabilities are accelerating.”

Park Ji-young, a nuclear policy analyst at the Asan Institute for Policy Studies in Seoul, said officials did not want to discuss the North’s new capabilities “because they don’t know exactly how they can stop them, and because they don’t want to scare the people.”

A master of bombast, Kim appears increasingly volatile during his fifth year in power. In a speech on Friday to the first congress of his Workers’ Party in 36 years, he boasted that his nuclear weapons and missile programs brought his country “dignity and national power.”

A few weeks ago, he posed with what appeared to be a mock-up of a small nuclear warhead, and his government released a video depicting a nuclear strike on the Lincoln Memorial.

But experts say North Korea is years away from deploying an intercontinental ballistic missile capable of striking the mainland United States with a nuclear payload, and even then no one sees the backward nation taking the enormous strides needed to build a much more destructive hydrogen warhead, capable of leveling cities.

Still, the North’s new capabilities have prompted a rethinking of U.S. military strategy in Asia. “We know they have nuclear weapons and the means to deliver them,” said Gen. Robert B. Neller, commandant of the Marine Corps. “If that’s where they are going, that changes the calculus.”

For President Barack Obama, who has completed a nuclear deal with Iran and renewed diplomatic relations with Cuba and Myanmar, the advances in North Korea highlight its status as the rogue state that got away.

Obama has pursued a policy of “strategic patience” — not overreacting to the North’s missile and nuclear tests, while using sanctions to press it to negotiate. But North Korea has refused to accept his demand that it commit to denuclearization as a goal before talks begin.

Instead, it has accelerated its nuclear effort, conducting tests in 2006, 2009 and 2013, and in January. The two most recent tests took place under Kim, and South Korean officials say the North may attempt a fifth nuclear test soon, perhaps to mark the party congress.

In March, Kim specified that the next test should involve a “nuclear warhead explosion.” Analysts said that suggested that the North might be on the verge of demonstrating progress in making a smaller device, building on previous tests that were perhaps more focused on the basics of detonation.

Shrinking a nuclear weapon is important because the smaller it is, the easier it will be for a missile to lift it and the farther the missile can fly. U.S. and South Korean officials said they believed that North Korea could make a nuclear warhead small enough to mount on its midrange Nodong missile, which usually carries a 1,500-pound payload but can carry as much as 2,200 pounds over shorter distances.

“Given the time that has elapsed since its first nuclear test, we believe that North Korea has achieved a significant level of miniaturization,” Han Min-koo, South Korea’s defense minister, said in March. He also noted that North Korea had conducted more missile tests under Kim than during his father’s entire 17-year rule.

But, Han said, the North has not mastered the complex technology needed to protect a nuclear warhead from destruction as an intercontinental ballistic missile re-enters the atmosphere.

Soon after Kim took power, U.S. satellites began picking up pictures of mobile missile launchers, which are harder to find and to target.

The missile launchers were of Chinese design, and the missiles resembled Russian weaponry. The Nodong, sometimes spelled Rodong, is a modified version of the Scud missile and can reach U.S. bases in Japan. Another missile, the Musudan, can target U.S. bases as far as Guam.

North Korea tested the Musudan three times, but it crashed into the sea or exploded seconds after takeoff each time. North Korea also has a long record of problems in its effort to develop intercontinental missiles, including an embarrassing failure in April 2012, just months after Kim took power.

But there have been enough successes to worry U.S. commanders. In February, North Korea put a satellite in orbit with a three-stage rocket that, if successfully reconfigured as a missile, some analysts believe could reach the West Coast of the United States.

A new concern is recent tests of a submarine-launched missile are a new concern. Deployment is likely years away. But submarines could stealthily move missiles within range of additional targets and give the North a “second strike” capability — to launch after its land-based arsenal has been destroyed.

North Korea first claimed to have launched a ballistic missile from a submarine a year ago, but photos released of Kim observing the test appeared to have been doctored. Video released from another test in December suggested that the missile was launched from a sunken barge, not a submarine.

On April 23, North Korea conducted another launch, apparently from a 2,000-ton Sinpo-class submarine. But the missile did not travel far, officials said.

John Schilling, an expert on North Korea’s missile program, has estimated that the North may have an operational system by 2020. But its current submarines are old and noisy, must surface frequently and cannot make it across the Pacific to North America.

The question now, for both Obama and his successor, is whether to set new red lines beyond which the North Korean nuclear program cannot go — or whether drawing those lines will only encourage the North to step over them, as it has done before.

Gary Samore, Obama’s top nuclear adviser in his first term, said the policy of “strategic patience” had failed to change the North’s calculations. “But that doesn’t mean you just build more missile defenses and walk away,” he said. “We need some kind of process to begin to freeze what they are doing.”

The more progress North Korea makes, though, the less willing it may be to stop.

Robert J. Einhorn, a leading expert on proliferation, said a crucial question was whether Kim would dig in and “refuse to cap their capability before they are able to deliver an ICBM with a warhead to the homeland.”

There are concerns aside from missile capabilities. “Should developing a long-range nuclear missile be the next red line? Or does that make less sense when the North could sell a bomb to a terror group, or put one in a basement in a big city?” asked Sam Nunn, co-chairman of the Nuclear Threat Initiative.

For now, the new U.S. response looks a lot like the old U.S. response, with the same weakness: China’s fear of destabilizing its neighbor with sanctions that hurt too much.

New sanctions enacted with China’s support after the January nuclear test have the potential to bottle up North Korean ships as they visit ports around the world. But the sanctions are difficult to enforce, and there is no requirement to cut off fuel shipments, which come almost entirely from China.

“So far we have Kim Jung Un to thank for driving the Chinese in our direction,” Samore said. “But they are still primarily worried about a collapse in the North” that leaves South Korean and U.S. forces on the Chinese border.

© 2016 The New York Times Company