Once upon a time, an American leader made certain threats on the Korean Peninsula. He threatened to use nuclear weapons to end the danger from North Korea. He threatened China for supporting Pyongyang in its struggle against Seoul, and against America. He declared that the only acceptable outcome was an end to the North Korean regime.

The leader was Gen. Douglas MacArthur, and for his insubordination he was relieved of his command by President Truman, and later investigated by Congress.

Today, the leader making extravagant threats is the president himself, warning of "fire and fury" if North Korea doesn't cease its provocations. But almost immediately after making his threats, the national security establishment explained that his words should not be taken literally, not by North Korea, not by South Korea or Japan, and not by the press. Not that America wasn't taking the North Korean threat seriously — but no "fire and fury" was planned.

The secretary of defense and secretary of state have not relieved the president of his command, but they have taken pains to let the world know that presidential statements should no longer be treated as policy.

This is a big problem.

The United States and North Korea are playing a high-stakes game of poker, but our hands look like they belong in different games. The United States has the overwhelming advantage in both hard and soft power, and we just demonstrated that advantage by getting the U.N. Security Council — including Russia and China — to unanimously endorse new sanctions against North Korea. The Hermit Kingdom's big card is their ability to blackmail the world with threats of mutual destruction: the huge number of artillery pieces facing Seoul, their growing nuclear stockpile, their missile program that has crossed the verge to intercontinental capability, and, not least, their knowledge that if their regime fell China and South Korea would inherit a humanitarian catastrophe.

When you are playing a high-stakes game like this, it makes sense to keep your cards close to your vest. We don't want the other side to know exactly what we would be willing to do, or what we would be willing to accept. But it is also necessary to be able to communicate what we want to, when we want to.

The United States' ability to deter North Korea depends on them believing that there is some point beyond which provocation would trigger a military response, notwithstanding the damage North Korea could do to America and (much more so) our allies. Our ability to entice them to the negotiating table depends on them believing that adequate concessions on their part might lead us to leave the Pyongyang regime alone — perhaps even formally end the Korean War and recognize the North. We need to keep the details unknown, or we have no room to maneuver — but if either path is entirely foreclosed, then deterrence collapses.

North Korea has, predictably, responded to Trump's threat-mongering with further threat-mongering of their own, targeting Guam in language far more specific than its usual braggadocio. And the national security adviser has acknowledged that the United States is "prepared" to launch a preventative war — language which falls well short of saying that such an assault is "planned," but clearly intended to warn the North Koreans of the potentially catastrophic consequences of continued recalcitrance.

But how can the North Koreans know whether this truly constitutes policy, or whether it is an attempt to bolster what amounts to a presidential bluff?

The simple answer is: They can't. The North Koreans can evaluate our capabilities, but they can't be sure that they have perfect knowledge of these. They have no way of knowing whether the Trump administration is genuinely committed to preventative war or not, though the fact that they have done virtually nothing to prepare the ground for conflict may incline them to believe that Trump's threats are all bluff. They have no way of knowing whether the Trump administration is open to a negotiated solution or not, or what might be on the table if negotiations resumed.

They do not know, when Rex Tillerson speaks, whether he speaks for the administration, or whether he is speaking to the administration. Most important, the same is true of the president himself: They cannot know whether his statements will be supported or undermined by his own staff, nor can they know whether his staff will be punished for such insubordination or be rewarded for it. The buck stops nowhere. They have no idea who's holding the cards.

All leaders rely on ambiguity to provide themselves with flexibility as circumstances change. And all leaders give their subordinates a certain amount of rope in order to explore possibilities without committing the government prematurely. But if there is no coherent chain of command, it is impossible either for threats or for negotiations to be credible. And in those circumstances, it may be entirely rational for the North Koreans to think that their best option is to call America's bluff.

The best card in Pyongyang's hand may be Trump.