What we learned from the Korean War

July 27 marks the seventieth anniversary of the armistice that ended major hostilities on the Korean Peninsula. Sometimes referred to as the Forgotten War, the last thing the Korean War should be is forgotten. First and foremost because tens of thousands of US and allied soldiers and millions of Koreans died, but also because of the lessons the war offers for policymakers today as the world enters an era not unlike the budding Cold War in 1950. 

The first lesson is on the importance of messaging. The world pays attention to what the US says, and Washington’s adversaries pay particularly close attention. In January 1950, secretary of state Dean Acheson spoke to the National Press Club about a perimeter that the US would defend against communist aggression. The problem was that South Korea was not within the perimeter. It has long been debated just how much impact the speech had in convincing (giving the “green light” to) Stalin to accede to Kim Il-sung’s plan to invade, but it was certainly a grave mistake. As Miles Yu of the Hoover Institution says, “with both a red light and a green light… [the speech] was the worst possible choice, the mixture of green and red: yellow.” In other words, it projected confusion — Acheson’s intent was to deter, but he may have unintentionally provoked. It does not matter how stern or resolute the first half of the sentence is if the second half leaves the adversary wondering if there is wiggle room — and expansionist autocrats will always push the envelope.

Biden’s faulty messaging on Ukraine is a modern case in point. Between the withdrawal from Afghanistan, lackluster pre-invasion military aid, the “minor incursion” comment, and other blunders, the message sent to Putin was: the US did not see Ukraine as a vital national security priority. Biden certainly did not intend that to be the message, but that was how it was received in Moscow — and ultimately, it is only the reception that matters. The result? February 24, 2022.

North Korea launched its invasion of the South on June 25, 1950, backed by Stalin and Mao both politically and, eventually, with thousands of Soviet and hundreds of thousands of Chinese troops. After three years of fighting, dramatic reversals and brutal stalemate, the war was brought to a halt by an armistice seventy years ago. Unlike a similar anniversary for the end of World War Two, the Korean War is, technically, still ongoing — the US, South Korea and North Korea have yet to sign a treaty ending the conflict. The border between the North and the South is today the most militarized in the world, and violence and provocation are not unusual occurrences — such as the Second Battle of Yeonpyeong, the subject of a South Korean film, Northern Limit Line. Soldiers on both sides still train their weapons at one another, and North Korea has metastasized into a nuclear weapons state aided and abetted by the CCP in Beijing. Pyongyang remains a serious concern for US national security despite its size, and thousands of US troops are stationed in South Korea.

This is lesson number two: frozen conflicts should be avoided. Every conflict is unique, so the reasons for why one gets frozen are case dependent, but the desirability of avoiding a freeze is nonetheless fairly constant. With that in mind, making sure Ukraine ends in a victory for Kyiv rather than with a European DMZ is critical. Biden and many of his European allies have dragged their feet in giving Ukraine the weapons it needs most, making its advance in the current counteroffensive much more difficult and costly. If Ukraine fails to sever Russian lines this year, a frozen conflict — spurred on by political frailty and war weariness in the West — becomes more likely. Should that happen, the threat of Russia will be held on a constant simmer for decades into the future, with the frontlines on tenterhooks and escalation an ever present possibility. Indeed, Russia used the lines from the 2014 invasion as jumping-off points for the 2022 invasion.

One of the key elements that has kept relative peace on the Korean Peninsula despite the frozen conflict, though, is America’s treaty-bound commitment to defend South Korea. Had that commitment not been there, there is little reason to believe that North Korea would not have reinvaded long ago. Maybe South Korea would have developed nuclear weapons to compensate, having another India-Pakistan situation in Asia does not exactly promise stability either, and nuclear proliferation carries significant dangers in itself.

Hence the third lesson: Ukraine needs to join NATO as soon as the war ends. The Biden administration blew this opportunity in Vilnius earlier this month, a decision that may cost the lives of thousands of Ukrainians and make the conflict drag on for much longer than it should. Russia will never attack Ukraine again if it knows that the full might of NATO will come to Kyiv’s assistance, just as North Korea, despite its over-the-top rhetoric, has not launched another invasion of the South. Only treaty-bound commitments have the staying power and trust needed to deter adversaries, because as the 1994 Budapest Memorandum and the 2022 Russian invasion showed, the US and the Europeans do not honor non-treaty commitments. 

The theme that underlies all of these lessons, however, is the necessity of US leadership. South Korea would not exist — and the borders of communism would have grown much larger — had the US not stepped up to stop communist expansion in its tracks. A prosperous and strong South Korea has been a massive benefit for the United States, and it remains a solid ally. Much of the world rallied around the US in its push to defend South Korea in 1950, with a truly multinational force coming to Seoul’s aid. The world will still rally around the US today — and has in the support of Ukraine — but that will not happen unless America leads.