News of North Korea’s test Sunday of a nuclear device drew angry reactions from its neighbors, allies, and the international community, as well as prescriptions of how to respond to the latest provocation, ranging from dialogue, to more sanctions, and “a massive military response.”

The two main proposals put forward so far are tougher international sanctions, an idea promoted by the U.S., and the so-called “freeze for freeze,” favored by China, in which the U.S. freezes military exercises with South Korea in exchange for the North freezing its missile and nuclear tests. Both those ideas have critics: Russian President Vladimir Putin, whose country is under U.S. and EU sanctions for its invasion of Ukraine’s Crimea, dismissed sanctions. “They’d rather eat grass than abandon their [nuclear weapons] program unless they feel secure,” he said Tuesday. Nikki Haley, the U.S. ambassador to the UN, called the “freeze-for-freeze” idea “insulting.” Decision makers seem to have much clearer ideas about what won’t work than about what will—and that’s in part due to the history of failed efforts to rein in North Korea’s nuclear program.

Here’s a look at the options that have been tried with North Korea, how they unfolded, and how they ultimately resulted in the situation we find ourselves now.

Talks: Direct U.S.-North Korean talks during the Clinton administration in the 1990s resulted in the Agreed Framework, under which Pyongyang said it would, among other steps, ultimately end its nuclear program in exchange for two light-water nuclear reactors and heavy-fuel oil shipments.

Under the deal, North Korea froze its nuclear program from 1994 to 2003 and, as the Arms Control Association points out, without this freeze “North Korea could have enough plutonium for more than 100 nuclear warheads today.” (The Kim Jong Un regime is estimated to have up to 60 warheads.)

The Agreed Framework was fraying by the end of the Clinton administration, with both sides failing to fulfill some requirements, but the Bush administration withdrew from it entirely. But beginning in 2003, the Bush administration engaged in six-party talks, involving China, Japan, North Korea, Russia, South Korea, and the United States, in an effort to persuade North Korea to renounce its nuclear ambitions. North Korea’s first nuclear test was conducted in 2006, making the urgency of talks all the more apparent. From 2003 to 2008, six rounds of multilateral talks persuaded the North to freeze its nuclear facilities, suspend some nuclear activity, and commit to full denuclearization. But the talks eventually broke down over disputes over verification after the North refused to allow inspectors to visit its facilities.

The Obama administration tried briefly—and failed—to talk directly with the North before resorting to a policy of “strategic patience,” which attempted to isolate North Korea without offering it any inducements to change its behavior. The Trump administration declared that the era of “strategic patience was over,” labeling its posture “maximum pressure and engagement,” but critics say it resembles the Obama approach.

“The Trump administration’s policy on paper makes sense,” Daryl Kimball, the executive director of the Arms Control Association, told me. “The problem is that they have not effectively implemented the full range of options that label implies, and there has been an almost exclusive focus on trying to increase the pressure. There has been no engagement with North Korea to explore a diplomatic engagement, and the policy limitation has been sabotaged by the president’s impulsive tweets, his threats of military action, which have only reinforced North Korea’s existing paranoia about the possibility of an American attack or decapitation strike.”

North Korea says it is open to dialogue with the U.S. if Washington ends its “hostile” policies, including military exercises with South Korea and sanctions. The U.S. sees these demands as nonstarters as long as the North continues to conduct nuclear and missile tests.

“We are caught in this cycle where each side claims to be open to talks but has set conditions that are not been met,” Kimball said, “and so the talks have not occurred.”

Sanctions: International sanctions have been in place on North Korea for a little more than a decade, and were tightened last month. The first major U.S. sanctions were imposed during the Obama years and targeted North Korean individuals and entities. Yet the North has continued to develop its nuclear and missile programs and is able and willing to find partners who flout international law and do business with it.

Andrea Berger, a senior research associate at the Middlebury Institute of International Studies, told me that international sanctions designed against North Korea until 2016 were limited; international attention to implementing those sanctions was not particularly high; that North Korea has a proven track record of sanctions evasion; and that it is now domestically making many of the parts needed for its prohibited programs.

“They are able to get around the obstacles we put in place overseas faster than we can erect those obstacles,” Berger said. “And it’s because they’re practiced in it for decades.”

Kimball pointed out that another round of international sanctions by itself isn’t going to halt the North Koreans nuclear and ballistic missile tests “because they are very determined that they have the capability to deter what they see as American aggression.”

Pressure on China: The Trump administration, and others before it, have urged China to do more to pressure North Korea to renounce its banned programs. But China, the Kim regime’s main political benefactor and largest trading partner, maintains its influence over Pyongyang is limited—even if its stated goal is to see a denuclearized Korean Peninsula. Chinese experts point out “we are right now at the lowest point in the relationship between China and North Korea.” Beijing also does not want an unstable North Korea at its border and has called for the “freeze-for-freeze” as a way to end the present impasse. China played a major role during the six-party talks, hosting all the rounds, and persuading what was then the Kim Jong Il regime to make concessions in exchange for some relief, but the country’s relationship with Kim Jong Un is more complicated, with the current North Korean leader less amenable to taking direction from Beijing.

Military options: A military strike by the U.S. against North Korea, while highly unlikely, has been raised as a possibility by President Trump who at various points over the last month said the U.S. would respond with “fire and fury” to North Korean aggression, that the U.S. military was “locked and loaded,” and that the U.S. nuclear arsenal is adequate to punish the North if needed. This position, while underscoring the North’s fear that the U.S. wants to destroy it, is unlikely to have any real impact: Experts point out that a tactical strike on North Korea is unlikely to take out its nuclear capability because Pyongyang has kept much of its assets hidden. A military strike would also prompt a North Korean response that could put the lives of tens of millions of people, including U.S. military personnel in Japan and South Korea, in danger. It’s worth noting that the 1950-53 Korean War—fought without a looming nuclear threat—ended in a stalemate and the division of the Korean Peninsula. The threat of conflict today is far more ominous.  

What makes the North Korean nuclear problem so maddeningly difficult is not the absence of options. There are plenty of options for dealing with North Korea. It’s just that many have already been tried, and most of them haven’t worked.