SEOUL, SOUTH KOREA —
Undeterred by international rebukes and increased sanctions in 2016, North Korea set forth to advance and legitimize its nuclear and ballistic missile programs, but then paused suddenly, most likely to assess unexpected political changes underway in the United States and South Korea.
North Korea began the year with a powerful nuclear bomb blast in January that caused a magnitude 5.1 earthquake. The state-controlled news organization KCNA claimed the military had successfully tested a miniaturized thermonuclear hydrogen bomb 100 times more powerful than past weapons tested.
But some analysts were skeptical. An examination of air samples and seismic data indicated the explosion was not powerful enough to be an H-bomb, and was more likely a conventional nuclear bomb made with enhanced fuels.
The nuclear test ended a brief period of inter-Korean cooperation during which the North and South arranged a rare reunion for families separated by decades of division and considered other types of nonpolitical exchanges.
With the January test, North Korean leader Kim Jong Un was setting a new, uncompromising and defiant tone, openly declaring his intention to force the world to accept his country as a nuclear state, and rejecting U.N. Security Council resolutions banning the North's nuclear and missile programs.
Regional security analyst Daniel Pinkston said that beyond the existential threat to the world posed by permitting the unpredictable and repressive North Korean state to possess these weapons of mass destruction, acquiescing to Pyongyang's demand to withdraw from the Nuclear Nonproliferation Treaty it signed in the 1980s could also spark a new global arms race.
"If other states were to look at this and say, 'Well, we can do that as well. There are no costs to nuclear breakout. We would like to acquire our nuclear deterrence as well, because it's basically costless,' I think that makes the world a much more dangerous place," said Pinkston, a lecturer in international relations at Troy University in Seoul.
In early February, North Korea launched a rocket into space that it called a peaceful "earth observation satellite." The United States and its allies denounced the launch as a disguised intercontinental ballistic missile test.
In response, South Korea cut all remaining ties with the North, including closing the jointly operated Kaesong Industrial Complex that employed 54,000 North Koreans.
A month later, the United States and China co-sponsored the passage of tough new U.N. sanctions that imposed a total arms embargo and increased financial and trade restrictions on North Korea.
The new sanctions did have some impact. Traffic at the busy Sino-Korean border, where most trade with North Korea occurs, was significantly reduced. There were reports in China that currency transfers to North Korean banks had been suspended and North Korean vessels had been prohibited from entering Chinese ports.
Some analysts say sanctions, and decades of political isolation and rigid state control, have worked to stifle economic growth in North Korea, especially when compared with the dynamic development achieved in such neighboring countries as South Korea, Japan and China.
"I would say that North Korea is the sick man in East Asia when it comes to economic development. So they can pay a very, very high price for this program," said Pinkston.
But Beijing has also seemed reluctant to strictly enforce restrictions that could spark instability. In particular, China continued to permit the billion-dollar coal export trade as well as trade in other lucrative minerals by exercising a humanitarian exemption in the sanctions.
Despite the increased sanctions, Andrei Lankov, a professor of Korean studies at Kookmin University in Seoul, noted that North Korea's economy continues to grow because of a thriving illegal but tolerated private sector and agriculture reforms that give farmers a greater share of their crops.
In a Korea Times editorial, Lankov wrote that Kim "might be ridiculed and dismissed overseas, but continues to enjoy support at home for good reason: Under his watch the vast majority of North Koreans live better, if still poor, lives."
Pyongyang responded to the sanctions by defiantly accelerating its weapons development programs through the summer, testing numerous land-based and submarine-launched ballistic missiles.
The U.S. responded to the ongoing provocations by moving more military assets onto the Korean Peninsula and conducting the largest joint military exercises ever with South Korea. The drills reportedly included preemptive military strike scenarios against North Korean nuclear sites.
Seoul also agreed to deploy the controversial THAAD missile defense system in South Korea, a move that China denounced as a threatening escalation of American military power in the region.
On September 9, North Korea conducted an unprecedented second nuclear test in one year. The U.N. followed with further sanctions that limit coal and mineral exports.
U.N. Secretary-General Ban Ki-moon expressed frustration and regret that diplomacy had seemingly failed to find a peaceful resolution to the political and military standoff.
"I'm deeply concerned [about] the mounting tension on the Korean Peninsula imposed by North Korea's ballistic missile tests as well as nuclear tests. The Security Council has met 10 times this year only; this is unprecedented that the Security Council is meeting 10 times for one single agenda," Ban said.
But in late September, North Korea paused all provocations, seemingly unsure how to respond to a South Korea corruption scandal that led to the December impeachment of adversary President Park Geun-hye.
Park's downfall is likely to lead to a reassessment of her hard-line North Korea polices. Some opposition leaders in Seoul have already called for the THAAD deployment to be delayed to appease China. One of the opposition leaders expected to run in the early presidential election next year, if the Constitution Court upholds the impeachment, supports renewing dialogue and some level of cooperation with Pyongyang.
The Kim Jong Un leadership also seems uncertain about how to react to the U.S. presidential election of Donald Trump. Trump's views on North Korea are unclear, and some hawkish members of his Republican Party are urging him to take a tougher stand against Pyongyang.
During the campaign, Trump had also been critical of South Korea, saying Seoul had not fairly reimbursed the United States for the cost of stationing 28,000 American troops in the country. However after the election, the president-elect did offer some reassurance he would continue to uphold U.S. regional security commitments.
Analysts expect North Korea to soon test the new leadership in Seoul and Washington. And how they respond could either create new opportunities for dialogue or increase the risk of conflict.
Youmi Kim in Seoul and Margaret Besheer at the United Nations contributed to this report.