After an unprecedented series of meetings between U.S. President Donald Trump and North Korean leader Kim Jong Un, negotiations over eliminating the latter’s nuclear arsenal have stalled. In the meantime, Kim has been busy making his nuclear arsenal bigger, deadlier and better able to strike South Korea, Japan, American forces stationed in Asia -- and the U.S. mainland.

1. Could Kim really hit the U.S.?

He appears to be rapidly closing on that capability. North Korea could likely fit miniature warheads onto missiles and shoot them far enough. (It successfully tested an intercontinental ballistic missile in 2017.) It has also developed weapons that can be moved around more swiftly to evade detection. What’s less clear is whether Kim’s military could beat antimissile systems and survive reentry, or if its weapons are refined enough to strike their intended targets.

2. What about its bombs?

Of North Korea’s six atomic tests, Kim was responsible for four. They’ve come a long way since the first detonation in 2006 which measured less than one kiloton, leaving experts wondering whether it had been a partial failure. (A kiloton is equal to the force of 1,000 tons of TNT). The most recent, in September 2017, was the most powerful. Its estimated yield of 120-250 kilotons dwarfed the 15-20 kiloton U.S. bombs that destroyed Hiroshima and Nagasaki in 1945. Experts estimate that North Korea has assembled 20-30 nuclear warheads, the fewest among the nine nations with nuclear weapons.

3. How are North Korea’s weapons more nimble?

Kim has rolled out new solid-fuel ballistic missiles that are easier to move, hide and fire than many liquid-fuel versions. He has launched some two dozen since May including nuclear-capable, hypersonic KN-23 missiles that can strike all of South Korea -- including U.S. forces stationed south of Seoul -- within two minutes. He has also launched KN-25 short-range missiles designed to be fired in rapid succession from a single launcher to overwhelm interceptors. The new ballistic Pukguksong-3 missile -- the biggest of the bunch -- is designed to be fired from a submarine and has an estimated range of 1,900 kilometers (1,200 miles). Weapons experts say North Korea also is developing an ICBM that uses solid-propellant technology, potentially giving the U.S. less warning ahead of any strike aimed at the mainland.

4. Where does Kim’s military get its fissile material?

It has been self-sufficient for decades. The program, which once turned out enough plutonium for one nuclear bomb a year, now relies largely on uranium enrichment and, according to weapons experts, produces enough fissile material for about six bombs a year. The Trump administration says North Korea has enlarged its stockpile since nuclear talks began. Experts estimate the country has enough for roughly 30-60 nuclear weapons.

5. What other surprises might be out there?

North Korea may be working on ICBMs that carry multiple warheads and in-flight countermeasures to throw interceptors off the trail, according to Datayo, an open-source weapons research site. Kim has pushed to develop his fleet of submarines and is looking to deploy a new vessel soon that experts say could fire missiles. He may even try to revive the country’s satellite program, arguing that North Korea has the right as a sovereign state to develop a space program. Weapons experts say satellite launches could be used by North Korea to advance missile technology.

6. How big are North Korea’s conventional forces?

Despite being among the world’s poorest countries, North Korea has one of the largest militaries. Of its 25 million population, nearly 1.2 million people are in active service, according to a U.S. State Department report. On top of that, more than 6 million North Koreans are considered reserve soldiers. The military has thousands of pieces of artillery trained on the Seoul area and hundreds of missiles that can strike South Korea and Japan.

7. How can the country afford all this?

The money needed is not huge in global terms. North Korea spent nearly $4 billion on its military in 2016, according to the State Department report -- roughly equivalent to two days’ U.S. military spending. As a share of its economy, though, the outlay ranks among the highest globally, if not the highest. Although international sanctions have hit the economy hard, North Korea is evading some through such means as clandestine, high-seas transfers of banned goods such as oil, and generating enough cash to keep its nuclear program moving through methods that include ransomware attacks.

8. Wasn’t Trump going to fix this?

Trump’s talks with Kim, beginning with a much-heralded meeting in Singapore in June 2018, turned the duo from insult-throwing enemies into dialogue partners. Trump says his diplomacy with Pyongyang prevented a war. But their three meetings have yet to produce a significant breakthrough -- and the North Korean missile testing and name-calling have resumed. North Korea has become what three decades of diplomacy had tried to prevent -- a state capable of developing, projecting and detonating atomic bombs. The U.S. military is maintaining its customary “high levels of readiness” on the Korean Peninsula as a deterrent to any threat, General Mark Milley, chairman of the Joint Chiefs of Staff, said in December.

To contact the reporter on this story: Jon Herskovitz in Tokyo at jherskovitz@bloomberg.net

To contact the editors responsible for this story: Brendan Scott at bscott66@bloomberg.net, Grant Clark, Paul Geitner

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