The White House press corps should ask President Obama this question: You’ve told Iran’s leaders that if they come close to marrying a nuclear warhead with a missile that can hit the United States or our allies, they should expect a U.S. military attack on their soil. Specifically, Mr. Obama, you said your policy on Iranian nukes was “prevention,” not “containment” or “deterrence.” You were not nearly as tough, specific, and threatening to North Korea.

Why? Is North Korea less dangerous than Iran, or more? Is President Ahmadinejad crazier than Kim Jong-un, or less? Is Pyongyang so far down the line toward developing deliverable nukes that you can’t stop them anymore, while Tehran still has a ways to go? Is it that Israel is more important to American security than South Korea and Japan? The very questions are spooky, and the answers Obama eventually will have to supply, in one fashion or another, will be dangerous. But given what he’s said about Iran and not said about North Korea, he’d better ready those answers now. Obama and his team deserve lots of credit for their handling of the crisis on the Korean peninsula. They’ve sent tough military signals, deploying bombers and missile defenses without any provocative bluster. They’ve avoided looking weak by begging for negotiations, but they’ve plainly not closed the door to talks initiated by Pyongyang. They’ve waited patiently for China, the one party capable of restraining North Korea, to grow frustrated with Pyongyang’s escalation. All quite skillful. But both Tehran and Pyongyang couldn’t help but notice the contradiction at the center of Washington’s anti-nuclear-proliferation policies—and that awareness will make both countries less willing to compromise. Iran’s diplomats see that Obama is being much tougher on them than on anyone else, especially North Korea. They’re thinking that Pyongyang’s pressing ahead with its nuclear-weapons program has given pause to Washington’s hard line and made Americans more willing to live with nukes there than in Iran. So, expect Tehran to stiffen its own position, as seems to have happened already in the failed meeting with the major powers last week. And Pyongyang’s leaders will see that Washington’s treatment of them is much more careful than its handling of Tehran and also attribute that to their unbending determination to go nuclear. They, like Iran, will be more resistant to compromise.

It’s not that Washington’s experts see North Korean leaders as nuttier than their Iranian counterparts. Indeed, Ahmadinejad was thought to be the nuttiest nut in Tehran and now seems to be chief advocate of negotiations, while the big boss Ayatollah Khamenei, honestly or not, forswears nukes. By contrast, Pyongyang’s tyrants pledge their allegiance to deploying nuclear weapons come what may, attended by periodic war dances. Yet, Western intelligence tends to belittle them as a bunch of bluffers. And it’s not that U.S. intelligence knows much about what’s going on in Pyongyang. Indeed, it doesn’t know whether the true boss there now is Kim Jong-un or his aunt and uncle or the generals or what or why.

Nor does Washington’s policy contradiction stem from the fact that North Korea now has developed sufficient nuclear and missile skills and it’s too late for the U.S. to do anything about them. Yes, Pyongyang is more advanced on these fronts than Tehran. But U.S. intelligence reckons that Pyongyang can’t even launch a nuclear-tipped missile at South Korea or Japan (only a conventional warhead). But Pyongyang’s leaders certainly don’t have the capability to launch a nuclear strike against Guam or Hawaii, let alone continental America, and won’t for many years. So, in theory, the United States can still stop important advances in North Korea’s nuclear striking power.

Administration officials would never admit it, but the main reason for their being tougher on Iran than North Korea seems tied to American domestic politics as much as or more than anything else, specifically the standing of Israel and oil versus Korea and Japan. On strictly foreign-policy and national-security grounds, Democratic and Republican officials surely regard Seoul and Tokyo as important as the Mideast, certainly now with the growing importance of Asia. In American politics, however, Israel and oil count for much, much more. It’s notable that President Obama made his strongest pronouncements about employing force to stop Iranian nukes at the annual meeting of AIPAC, the very potent group of American-Jewish backers of Israel. There is nothing remotely comparable for any and all Asian countries, whatever the strategic and economic criticality of Asia.

What’s truly at stake here are American efforts to stop the proliferation of nuclear weapons. This latest Korean crisis may send South Koreans and Japanese on their way toward nukes. After all, their leaders are bound to reason that while the U.S. will defend them if attacked, the U.S. won’t go to war to “prevent” others in their region from acquiring nukes. So, they might well conclude that their best bet is to put their security in their own hands and go nuclear—just like Israel.

What’s happening in Korea is potentially momentous: either there will be a terribly costly war with the inevitable destruction of North Korea, or the world will find itself with at least two more nuclear-weapons powers.