On Feb. 10, Kim Yo Jong, the younger sister of North Korean leader Kim Jong Un, delivered a handwritten letter from her brother to South Korean President Moon Jae-in, inviting the latter to Pyongyang for what would be the third inter-Korea summit talks. Notably, Kim Yo Jong was the first Kim family member to ever travel to South Korea.

As The Washington Post reported, Moon walked a fine diplomatic line in his response, saying he wanted to “create the environment for that to be able to happen,” while simultaneously encouraging Pyongyang to “actively pursue” dialogue with the United States.

While many commentators focused on the overture and the response, few grasped that this offer was merely North Korea being North Korea: namely, employing a high degree of tactical flexibility in pursuit of two consistent, explicitly stated goals: consolidating and protecting the regime’s control in the north, and eventually completing the Kim family’s revolution and “liberating” the people in the south. Their long-term goal is one Korea, unified under Kim rule, and they are willing to try anything — even conflicting tactics — to achieve it.

The failure to understand that North Korea is flexible about anything but these fundamental goals — and will do whatever is necessary to pursue them — also precludes commentators from understanding another crucial truth: North Korea won’t attack the United States unless attacked first.

This isn’t the first time North Korea has called for talks with Seoul or Washington in pursuit of these broader aims. It’s a regular tactic aimed at fracturing the U.S.-South Korea alliance.

Early in the administration of President Jimmy Carter, Kim Il Sung (Kim Jong Un’s grandfather) tried to initiate direct talks with the United States while sidelining the “illegitimate” South Korean “Other.”

During the 1976 presidential campaign, candidate Carter publicly criticized the rampant human rights abuses in South Korea under military dictator Park Chung-hee, and also announced plans to remove all U.S. ground combat forces from the country. In the ongoing battle for inter-Korean legitimacy, the incoming Carter administration appeared, from Pyongyang’s perspective, potentially receptive to a new approach.

Upon Carter’s election, Kim Il Sung wasted little time. On Feb. 11, 1977, three weeks into Carter’s term, North Korean Foreign Minister Heo Dam sent a letter to Secretary of State Cyrus Vance declaring that North Korea wanted to “reduce tensions on the Korean Peninsula” and welcomed Carter’s “intention to remove U.S. troops and withdraw nuclear weapons from Korea.”

Heo claimed that Pyongyang had “continuously argued that . . . Korean unification should be resolved in a peaceful manner and frequently made clear that we have no intention to invade South Korea,” and “the DPRK and the United States should have active talks immediately in order to ease tensions and sustain peace on the Korean Peninsula.” But there was a catch: Pyongyang insisted that Seoul should only be included later, and even then should be represented by certain political and social groups of the North’s own choosing, rather than by the official South Korean government.

U.S. officials, such as National Security Council staff member Michael Armacost, properly perceived Heo’s offer as the latest iteration of Pyongyang’s willingness to employ any method to pursue its broader goal of “reunifying the Korean Peninsula on its own terms,” and approached it cautiously.

In a Feb. 28 memo to national security adviser Zbigniew Brzezinski, Armacost highlighted Pyongyang’s often shifting strategies, including its sometimes abrupt reversals. In the late 1960s, the North Koreans “pursued without notable success a confrontationist approach.” This phase, sometimes referred to as the Second Korean War, included a commando raid on the South Korean Blue House, seizure of the USS Pueblo and the downing of an American EC-121 spy plane. “Subsequently,” Armacost wrote, “it tried a ‘détente’ strategy culminating in the abortive North-South talks of 1972,” and thereafter “turned to a more adroit diplomatic offensive designed” to increase its own international standing “while putting the South on the defensive diplomatically and casting it in the role of the pariah.”

This last strategy had been complicated by the Aug. 18, 1976, ax murder of two U.S. Army officers by North Korean soldiers in the Joint Security Area at Panmunjom. But in light of Carter’s withdrawal policy, North Korea saw an opportunity to foster bilateral relations with the United States, a long-held goal.

According to Armacost, the United States should welcome Pyongyang’s apparent moderation and affirm its willingness to discuss matters related to the Korean Peninsula, but should also insist that any conversations had to include the South Korean government. Otherwise, he wrote, “We need not play their game on this.”

Although proposals for four-party talks, including China, were later explored, North Korea maintained its untenable demand that South Korean groups other than the government be included. Moreover, when Carter delayed and later scrapped his withdrawal policy, Pyongyang reverted to its standard anti-American line. By 1983, it had returned to outright aggression, blowing up the Martyrs’ Mausoleum in Rangoon in an attempt to assassinate Chun Doo-hwan, then president (and dictator) of South Korea. Chun survived; half his cabinet did not.

Clearly, there are notable differences between today and the late 1970s. South Korea’s democratization has opened space for Pyongyang to exploit domestic political cleavages more effectively than under Seoul’s Cold War military dictatorships. Moreover, from the U.S. perspective, Pyongyang’s nuclear and missile capabilities have transformed a case of extended deterrence (where the United States defended a distant ally from local attack) to one of immediate deterrence (where the U.S. mainland is itself threatened). This presents a qualitatively new threat and elicits profound concern. Such changes give Pyongyang new leverage with which to drive a wedge between Seoul and Washington.

Nevertheless, as history shows, Pyongyang’s ever-shifting behavior, from provocation to engagement and back again, is rooted in the Kim family regime’s laserlike focus on achieving its fundamental aims, which, in the profoundly constrained international environment in which it operates, means exploring any potentially viable strategy. As Korea specialist Andrei Lankov observes, the regime is neither irrational nor mindlessly ideological, but rather remarkably efficient and calculating, perhaps the best practitioner of Machiavellian politics in the modern world. Indeed, Pyongyang’s tendency to suddenly shift from aggressive behavior to cooperation is a demonstration not of insanity but of a hyper-rational flexibility.

The implication? Both the hawks and doves have it wrong on North Korea. Pyongyang won’t unilaterally start a war — one that would undoubtedly end in its own demise — but the regime also won’t relinquish the instruments of war it sees as guaranteeing its own survival. North Korea is neither suicidal nor willing to make fundamental concessions.

Everything it does is calculated to achieve its higher goals. Reunification on its own terms, by any means necessary, may be a long-term goal. But its own survival is a necessary precondition for achieving that. It will be aggressive, but it will not attack the United States or South Korea without being attacked first.

In short, this leaves the United States and South Korea where they have been: confronted by a highly militarized divide with few attractive options, the least worst of which is the maintenance of solid deterrence and unity against both Pyongyang’s threats and cajolery. They must remain steady, play the long game and prepare for the inevitable day when something real changes in Pyongyang.