The 2023-2024 Korean crisis was a period of heightened tensions between North Korea and South Korea that began on 28 December 2023 when North Korea's state media reported that Pyongyang's military and defense sectors would further accelerate war preparations in the face of US Navy exercises.
Throughout 2023, tensions between the Koreas simmered as North Korea launched several missile tests and made bellicose announcements; in December, North Korea launched a long-range Hwasong-18 ICBM capable of reaching the United States. On 17 December, North Korea's Defense Ministry announced that Washington DC and Seoul would finish the year with "a preview of a nuclear war." The United States responded by bolstering its assets in the region, including sending the USS Missouri nuclear-powered submarine to Busan in mid-December 2023. North Korea responded to this by declaring that a "critical situation" was pushing Pyongyang towards "more offensive" actions. On 19 December, the US, Japan, and South Korea jointly announced that they had activated a real time data-sharing mechanism to monitor North Korea's missile activity. On 5 January 2024, North Korea fired 200 artillery shells at Capes Jangsan and Sansan, near the disputed Yeonpyeong Island, forcing the island's evacuation.
On 15 January 2024, North Korean leader Kim Jong-un took a major escalatory step by calling for North Korea's constitution to be changed to ensure that South Korea was seen as the "primary foe", while placing the Korean People's Army on war footing. He also concluded that peaceful unification with the South was no longer possible, and he accused Seoul of seeking regime collapse and unification by absorption. While Kim said that he didn't want war, he had no intention of avoiding it, and he decided that North Korea should also plan to completely occupy, subjugate, and reclaim South Korea in the event of a war, severing all inter-Korean communication and calling for the destruction of a monument to reunification in Pyongyang. Scholar Siegfried Hecker said that the situation on the Korean Peninsula was "more dangerous than it ever has been" since the start of the Korean War in 1950, concluding that Kim Jong-un had made a strategic decision to go to war; he also said, "The danger is already far beyond the routine warnings in Washington, Seoul, and Tokyo about Pyongyang's provocations." At the same time, John Nilsson-Wright said that Kim's remarks were "unprecedented" and "unusual." In response to Kim's dangerous change of course, South Korean president Yoon Suk-yeol said that South Korea would respond "multiple times stronger" to any provocation from the north.
On 19 January 2024, North Korea announced that it detonated an underwater nuclear weapon system in response to trilateral drills by South Korea, the United States, and Japan. That same day, a Washington Post article reported that North Korea could be preparing for war, as North Korea's top military organization had held an unusual number of meetings in mid-2023, and Kim called for "preparations for a revolutionary war for accomplishing" reunification. Kim also vowed to expand his weapons arsenal in 2024 by launching new spy satellites, building military drones, and producing more nuclear materials. While Pyongyang knew that it would not survive an all-out nuclear war, it was theorized by the Atlantic Council that North Korea could find limited ways within the next decade to challenge the US-South Korean alliance.
On 23 January 2024, North Korea demolished the Reunification Arch in Pyongyang, and, that same day, North Korea launched its second round of missile launches that year, firing cruise missiles into the sea. The USA, South Korea, and Japan expanded their combined military exercises in response to the missile tests. By 25 January 2024, US officials assessed that North Korea could take some form of lethal military action against South Korea, namely strikes that could still avoid rapid escalation, like the bombardment of Yeonpyyeong in 2011.
Kim visiting troops in March 2024
In March 2024, Kim ordered heightened war preparations after inspecting troops at a major military operations base in the country's west. Kim ordered the steady intensification of actual war drills aimed at rapidly improving the KPA's combat capabilities for perfect war preparedness; his visit took place as the United States and South Korea continued their annual Freedom Shield large-scale military exercises. On 11 April 2024, the day after the South Korean legislative elections, Kim Jong-un said unstable geopolitical situations surrounding his country meant that North Korea should be more prepared for war than ever. Kim also threatened that, if provoked, North Korea would "deal a death blow to the enemy without hesitation by mobilizing all means in its possession."
On 23 April 2024, North Korea claimed to have tested a new nuclear weapons command-and-control system with a simulated counterstrike, testing the Haekbangashoe system for the first time. The crisis escalated further on 2 May 2024, when South Korea raised the terrorism alert for five diplomatic offices in the region due to North Korean threats to harm its officials. Seoul's embassies in Cambodia, Laos, Vietnam, Vladivostok, and Shenyang were placed on high alert as the National Intelligence Service said it had a "number of indications that North Korea is preparing to carry out terrorist attacks against our diplomatic officers and citizens." Pyongyang dispatched agents to those countries to surveil the South Korean missions, but the North's government criticized allegations of terrorism as US-led efforts to discredit America's opponents.
In May 2024, North Korea began to send balloons carrying trash bags across the South Korean border, claiming that its pollution campaign was retribution for South Korean propaganda broadcasts in the North. In response, South Korea suspended its side of the 2018 Panmunjom Declaration. In June 2024, North Korean soldiers repeatedly crossed the South Korean border before being chased off by warning shots, with South Korea determining that they had lost their way in the forest while planting additional landmines. On 19 June 2024, Russia and North Korea agreed to assist each other in the case of foreign aggression.
Tensions deteriorated as North Korea dispatched 11,000 troops to participate in the Russo-Ukrainian War; on 22 November, Russia repaid North Korea by sending air defense missiles to the DPRK. On 3 December 2024, President Yoon implemented martial law in South Korea, accusing the opposition of "anti-state activities" and promising "to safeguard a liberal South Korea from the threats posed by North Korea’s communist forces and to eliminate anti-state elements." However, the martial law crisis was resolved the same day when protests forced Yoon to call off his declaration; he was impeached days later.
On 6 January 2025, North Korea fired an intermediate-range ballistic missile toward the Sea of Japan in the country's first missile launch in two months, coinciding with Secretary of State Antony Blinken's visit to Seoul for talks with South Korean leaders.