The only thing more difficult than attempting to stop one rogue nation from acquiring nuclear weapons is attempting to stop two rogue nations collaborating to do so.

As we explore our options in shutting down North Korea’s nuclear weapons and missile programs, we must recognize we are also dealing with Iran’s programs, which have piggybacked upon Pyongyang’s. Ever since Iran’s war with Iraq (1980-1988), during which North Korea began providing Tehran with SCUD missiles, both countries nurtured a relationship that would allow them eventually to gain membership into the nuclear arms club.

In recent years, the evolution of this relationship has allowed Iran to step into the shoes of North Korea’s former and longtime best friend, China. It is also why China has been unresponsive to U.S. calls to reel Pyongyang in.

North Korea’s leadership behaves as if it has determined that it no longer needs China as its “big brother,” as Iran is committed to seeing Kim acquire a nuclear arsenal and delivery system for it. Tehran’s mullahs have not hesitated to use Pyongyang over the past several years as a test case for American resolve. As such resolve has been non-existent, Iran came to recognize it could move forward simultaneously and in coordination with Pyongyang.

Having developed this close working relationship, Iranian observers began showing up at North Korean military tests. It was also this relationship that led to North Korean technicians working secretly to build a nuclear facility in Syria. Its development was closely monitored by Israel which, after the U.S. refused to take action to stop construction, destroyed it in an air attack in September 2007.

Undoubtedly, this nuclear facility was yet another effort by Iran – this time using its Syrian proxy, President Bashir Assad – to test our resolve. While Tehran found ours lacking, Israel’s was not. One can only imagine, had Israel not destroyed it then, ISIS seeking to capture it later.

As we weigh what option to take with North Korea, we must recognize, first of all, decades of diplomacy and sanctions have never worked. Kim will only use any future diplomatic efforts to extract concessions, as has been done in the past, lulling us to believe the crisis is over when it is not. Kim will relentlessly continue his missile and nuclear program. His motivation for doing so is twofold: to achieve a nuclear deterrent and to add to his prestige as a world leader. He has vowed never to give up his nuclear program and, as such, would lose face in the eyes of his people if he does now.

What we must recognize, however, is that a North Korea capable of striking the US with nuclear weapons will result in nuclear conflict. Interestingly, this will not happen as a result of an attack initiated by Pyongyang. Kim is smart enough to understand the concept of Mutual Assured Destruction (MAD) by which any nuclear attack he launched against the US would lead to his own annihilation—obviously an outcome no narcissistic despot desires.

It will lead to a nuclear conflict in which Kim intends not to be a party, but a spectator.

The North Korean strongman has received millions of dollars from the Iranians to continue his programs to develop nuclear weapons and a delivery system. Undoubtedly, much of this funding has come from the billions of dollars Obama sent the mullahs while negotiating the nuclear deal. Such weapons will then be acquired by Tehran as well. And, as firm believers in the eschatological Mahdi prophecy, the mullahs view MAD not as a threat to their existence but as a means of attaining their afterlife in Paradise.

For Kim, it is all about money and prestige. But if we fail to take military action to deny him his nuclear goal, we do need to forewarn him that any nuclear attack by Iran against the US or an ally will be deemed an attack by North Korea as well.

Unfortunately, at least nine U.S. presidents have believed reason ultimately would trump North Korea’s behavior. It has not. In fact, dozens of acts of aggression by its leadership against the U.S. and our allies have been documented in a 2007 report to Congress—from attacking and capturing a US Navy ship to shooting down a US military plane to assassinating South Koreans to kidnapping Japanese to sinking an ROK frigate—all failing to generate a military response. It has only emboldened additional bad behavior, leading today to a situation in which the Pyongyang/Tehran nexus has stacked the deck against us as our viable options can only be described as “lousy.” It now leaves us more threatened than ever before by a nuclear attack.

Sadly, threatening Kim’s personal survival in the event such an attack by Iran occurs may be the only card we have left to play.

Lt. Colonel James G. Zumwalt, USMC (Ret.), is a retired Marine infantry officer who served in the Vietnam war, the U.S. invasion of Panama and the first Gulf war. He is the author of “Bare Feet, Iron Will–Stories from the Other Side of Vietnam’s Battlefields,” “Living the Juche Lie: North Korea’s Kim Dynasty” and “Doomsday: Iran–The Clock is Ticking.” He frequently writes on foreign policy and defense issues.