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

East Asia woke up this morning to a geopolitical nightmare, as tensions mounting from separate, ongoing incidents involving the Korean peninsula began to converge.

A military conflict doesn’t appear to be on the immediate horizon. But relations among a variety of nations—including China, Japan, North Korea, South Korea, Malaysia, and the United States—have been severely strained. Here’s a roundup of what happened.

A tussle over trade

At roughly 7:30am HKT, South Korea threatened to file trade complaints against China.

Lee Hyun-jae, chairman of the Liberty Korea Party’s policy committee, told reporters that the government might turn to the WTO in order to mitigate China’s retaliation against South Korean companies.

For months, authorities in China have thrown hurdles at South Korean businesses operating inside the country. K-pop stars have been barred from entering the country to perform concerts. Airlines applying to add charter flights from Korea to China have been denied access. Restrictions have been placed on Chinese tourists looking to travel to South Korea. Lotte Group, a Korean conglomerate with shopping centers and duty-free stores across China, saw 23 of its supermarkets close abruptly.

China has acted against these companies as a form of revenge for THAAD, the military system South Korea is developing with the United States. THAAD, which stands for Terminal High Altitude Area Defense, is designed to destroy missiles in mid-air, like hitting a bullet with a bullet. While it’s intended to prevent North Korea from launching ballistic missiles, China nevertheless views THAAD as a threat to its own military ambitions because it can conduct surveillance, and also marks a broader expansion of US defense forces in China’s direction.

Until this morning, South Korean authorities have hesitated to publicly draw a connection between THAAD and China’s economic retaliation. Now, by openly threatening to take its case to the WTO, South Korea is signaling it is willing to fight back.

Missiles on a mission

At roughly 8am HKT, North Korea acknowledged its most recent missile launch, which took place yesterday. State media outlet KCNA published an unusually direct article saying that it fired the rockets in hopes of eventually reaching US military bases in Japan. The piece described the missiles as “so accurate that they look like acrobatic flying corps in formation.”

Three of the four missiles landed a mere 350 km (217 miles) from coastal Japan, renewing fears of an attack.

The statement prompted Japanese prime minister Shinzo Abe to speak by telephone with US president Donald Trump. Abe told reporters that the two agreed the threat posed by North Korea “has entered a new stage.”

THAAD gets fast-tracked

At about 10am HKT, the US abruptly announced that overnight it had begun setting up the THAAD system, which should now be operational as early as April—months sooner than expected. Last November a US commander said the system would launch “in the next eight to 10 months.”

The US Pacific Command released a statement confirming it had moved the program’s “first elements” into South Korea. Meanwhile a video posted by United States Forces Korea shows what looks like military vehicles getting offloaded from a plane onto a vast runway, beside a building that bears the sign ”Welcome to Korea.”

Tightened borders

Just before noon, North Korean state media outlet KCNA published a notice saying North Korea had informed the Malaysian embassy in Pyongyang that it would “temporarily ban” the exit of Malaysian citizens from its borders. It said they’d be blocked ”until the safety of the diplomats and citizens of the DPRK in Malaysia is fully guaranteed through the fair settlement of the case that occurred in Malaysia.”

By “the case,” KCNA was referring to the murder of Kim Jong-nam, the older half-brother of North Korean leader Kim Jong-un. An effective exile from North Korea, Kim Jong-nam was killed in mid-February at Kuala Lumpur International Airport after two young women—one Vietnamese, one Indonesian—attacked him using one of the deadliest chemical weapons on Earth.

North Korea and Malaysia have for years maintained unusually cozy relations. Citizens of Malaysia could enter North Korea without a visa, and the two countries conducted rudimentary trading of raw materials and labor. Yet those warm ties quickly cooled after Kim’s death. Malaysian authorities conducted its investigation into the murder independently and without interference from Pyongyang, much to the latter’s chagrin. On Saturday Malaysia demanded North Korea’s ambassador leave the country within 48 hours, and Pyongyang responded in kind. Malaysia also sealed off the North Korean embassy, saying various diplomats were wanted for questioning by the police.

Yet North Korea’s restrictions on Malaysian nationals visiting the country considerably raises the stakes of the diplomatic row. It’s safe to say that Pyongyang is effectively holding another country’s citizens hostage—and if history serves as a precedent, arranging their release could be very difficult. Malaysia says 11 of its nationals are currently inside North Korea.

In response, Malaysian prime minister Najib Razak announced that a similar ban would be placed on all North Koreans residing in Malaysia. These restrictions are unlikely to carry the same weight, however, given the dire quality of life most North Koreans face. About 300 North Koreans currently live in Malaysia, most of them working as laborers.

What happens next?

As a best-case scenario, North Korea can be persuaded through diplomacy to free the detained Malaysians, and perhaps even roll back its nuclear program.

By now, though, that seems like wishful thinking. It’s easier to envision a deeper fallout. Beijing, which favors a stable, authoritarian North Korea, might express more support for the Kim regime. It could also express its opposition to THAAD by acting even more aggressively in the South China Sea, where it’s built militarized islands atop reefs, or the East China Sea.

With the US and South Korea committed to THAAD, China opposed to it, and North Korea increasingly erratic, it looks unlikely that the parties will achieve a middle ground anytime soon.

An earlier version of this post erroneously stated that South Korea, not Malaysia, sealed off the North Korean embassy. The error has been corrected.