How borders are drawn and enforced has far-reaching consequences, whether we live on either side of them or halfway across the world.

China’s top nuclear experts believe North Korea may be a much larger and immediate nuclear threat than previously believed.

According to the Wall Street Journal (paywall), Chinese uranium enrichment experts estimate Pyongyang has 20 nuclear warheads and enough weapons-grade uranium to double that arsenal within a year. The comments, made in a briefing with nuclear experts from the United States, are well above current US estimates of between 10 and 16 nuclear bombs.

Sanctions, international condemnation, and negotiations haven’t done much to dent the country’s nuclear ambitions. Pyongyang routinely threatens to nuke New York and turn Seoul into a lake of fire. Relations between North Korea and its longtime patrons in Beijing are also deteriorating.

North Korea watchers have increasingly argued that it may be too late to stop North Korea’s nuclear weapons program, which has also become a cautionary tale for critics of a proposed deal with Iran. Some experts say that international efforts should focus less on stopping uranium enrichment in the country and more on convincing Pyongyang to normalize relations with its neighbors and not export its nuclear technology.

Recent research suggests Pyongyang has been building its own centrifuges since at least 2009, and has at least one uranium-enrichment factory. US defense officials said earlier this month that North Korea may now be able to mount a nuclear warhead on an intercontinental ballistic missile, the KN-08, which some experts believe has a range of 5,600 miles, long enough to reach America’s western coast. US officials don’t believe the missile has been tested yet.