Despite the efforts of the last three American presidents, North Korea has continued advancing as a nuclear state. Can Donald Trump rein in the rogue state any better?
In a televised New Year's Day address to his nation, North Korean leader Kim Jong Un announced his resolve to develop a missile capable of reaching the U.S. mainland.
"We will continue to build up our self-defense capability, the pivot of which is the nuclear forces, and the capability for preemptive strike," he said.
President-elect Trump responded the next day on Twitter: "North Korea just stated that it is in the final stages of developing a nuclear weapon capable of reaching parts of the U.S. It won't happen!"
His confidence drew skepticism from many North Korea security analysts, who noted that the issue has long confounded the international community — and that Trump hasn't detailed a strategy for dealing with the North.
"It's just a statement of resolve without any indication of how he's going to prevent it," said John Delury, an associate professor of Chinese studies at Seoul's Yonsei University. "And, of course, it's all about the how."
The United States and its allies have tried a variety of tools to prevent North Korea, one of the world's most isolated countries, from developing and deploying nuclear weapons.
But diplomatic negotiations stalled in 2008, and a series of economic sanctions and aid have at times slowed, but not stopped, North Korea's nuclear ambitions.
In the 1990s, then-President Clinton helped win agreement to close a North Korean nuclear facility in exchange for aid — a deal that ultimately fell apart. His successor, George W. Bush, sought a change in government in Pyongyang.
The Obama administration has demanded that Pyongyang denuclearize while also trying to get other countries in the region to oppose the country's efforts.
The strategies haven't worked. Most security experts now believe North Korea is, in fact, an established nuclear state — perhaps possessing more than a dozen devices. A key question now, analysts such as Delury say, is whether the nation has the tools to deploy the weapons globally.
North Korea has numerous missiles, some of them mobile and outfitted with reengineered Russian technology. America's allies in the region, such as Japan and South Korea, whose capital is 120 miles from Pyongyang, are already on edge about short- and intermediate-range capabilities.
Long-range missiles remain a major goal, and in his New Year's speech, Kim said the North Korean military was close to testing an intercontinental ballistic missile.
Since he took power in late 2011, Kim has supervised tests for dozens of missiles, including some that, in theory, could be launched from submarines. His country has also tested at least three nuclear devices, drawing ire from much of the international community, including Pyongyang's longtime ally China.
Given the North's advances in missile development, Trump's administration now faces fewer options than previous presidents. Some include convincing North Korea that its nuclear program threatens the Pyongyang government's survival. There's also the possibility of a negotiated agreement involving regional countries — and perhaps more economic and political pressure from China and Russia.
Chun Yung-woo, a former South Korean national security advisor who has participated in talks with North Korea, sees in Trump's confident tweets a leader who finally might make headway with Kim.
"I see the advent of Trump as an opportunity," said Chun, now a senior advisor at the Asan Institute for Policy Studies in Seoul. "In dealing with unconventional leaders like Kim Jong Un, I think a leader like Trump, another unconventional leader, could help. I don't think a conventional approach works better."
Others are more skeptical.
Duyeon Kim, a Seoul-based researcher at Georgetown University's Institute of the Study of Diplomacy, questioned, for example, Trump's decision to weigh in on Twitter.
Trump punctuated his recent tweet with "It won't happen!" Does that mean Trump does not believe North Korea can achieve the missile capacity, she asked, or that he will find a way to stop it? She said the president-elect's public resolve could be an opportunity for diplomacy — or a disaster.
"I seriously hope Trump does not mean he will stop the North with force," she said. "Trump needs a real North Korea policy and strategy, and Twitter is not the forum through which to create one."
Melissa Hanham, a senior research associate at the James Martin Center for Nonproliferation Studies in California, said North Korea's desire for long-range missiles would be difficult for any president today to stop.
"I don't think there's any way that he's come up with a silver-bullet solution that he said in his tweet," said Hanham, who closely examines North Korea's propaganda photos to gather clues about its military capabilities. "This is actually a very complex quagmire with all sorts of variables that he can't stop with sheer force of will."
In his speech, Kim also left a narrow opening for a diplomatic solution, subtly suggesting that the nation might halt its work if the United States and South Korea stop their regular war exercises on the North's "doorstep."
Delury, the Yonsei professor, took to Twitter to discuss the diplomatic opening in Kim's remarks. He also noted that Trump had been relatively restrained in his tweets — not personally insulting Kim, for example. The North Koreans, in turn, haven't attacked Trump.
"They have left themselves room to at least explore what a preliminary deal might look like," he said.
Stiles is a special correspondent.