Just hours ago North Korea successfully tested what many consider to be intercontinental ballistic missile (ICBM) technology, underscoring the failure of two decades of U.S. policy. How Washington expected to halt Pyongyang’s missile development program without taking serious steps to do so remains a mystery. While ineffective policies date back to the previous Bush and Clinton administrations, the current administration bears its fair share of the blame.

President Obama made a serious error when he failed to order that the rocket launched in April be shot down — if not destroyed on the launch pad, admittedly a highly provocative act. Had he done so, he would have deprived the North Koreans of the lessons it learned from that missile’s failure and we might not be where we are today. In fact, had the president established a new precedent — the United States simply does not allow North Korea to conduct unfettered missile tests — he might have quickly made such tests a thing of the past.

But for whatever reason, when Pyongyang launched its rocket in April, the president chose to stick to an old playbook full of defensive formations that has never given North Korea pause. The State Department unwittingly admitted last week that the old approach — stern warnings before a launch, stepped up sanctions after — has all but failed. As spokesman Mark Toner explained at last Wednesday’s press briefing, “there’s always ways to toughen enforcement of sanctions. They can always be tweaked or modified so that there’s better enforcement of existing sanctions.”

In other words, existing sanctions are porous and have failed to stop North Korea from developing its missile technology. Mr. Toner was right to assert that present sanctions enforcement can be strengthened, but there is little reason to believe that China, Kim’s favorite enabler, will acquiesce in any effort to do so. Indeed, following Wednesday’s demonstration that North Korea is closer to acquiring the capacity to strike the United States, Beijing merely expressed “regret” that the test had occurred and appealed for “calm” from all sides, while making it a point to emphasize that “the Democratic People’s Republic of Korea has the right to make peaceful use of outer space,” albeit a restricted one in light of relevant UN Security Council resolutions.

If President Obama was mistaken in not adopting a more proactive approach in April, he was negligent in failing to do so this time around. New circumstances in North Korea virtually screamed for a novel approach in responding to the missile launch.

First, the Kim regime may actually be less stable today than it was back in April. Top military officers have continued to be purged since the summer, and, according to some estimates, Kim has now purged at least 31 top military officers since taking control of the country after the death of his father a year ago. While that suggests Kim has sufficient authority over personnel choices, it also suggests he may be struggling to find lieutenants he can trust. Reports that Kim goes nowhere without conspicuous armed guards and that he has stepped up repression of the hungry masses point to an insecure leader uncertain of his own safety.

Second, this launch marked the shortest-ever interval between North Korean long-range missile tests. The four previous tests occurred in 1998, 2006, 2009, and April 2012. The decision to conduct a second test this year may have indicated that the young Kim is desperate to consolidate his power over the military. But the stepped-up testing frequency also suggests Pyongyang is actually serious about developing a functioning intercontinental ballistic missile (ICBM), instead of simply using occasional tests to extract aid concessions from the international community. That the North’s rocket scientists apparently determined the causes of the April test’s failure and corrected those flaws should tell us that they are not to be underestimated.

Shooting the missile down would have undermined what is perhaps the regime’s greatest myth — that it is powerful and feared abroad. Now, that myth has been reinforced. Intercepting the rocket in flight might also have sown dissension within the ruling clique, as military and party leaders could not have helped but notice that the United States had never taken such bold action when Kim Jong-il was alive. But in sticking to the old script, Washington passed up an opportunity to destabilize the regime, a necessity if America’s ultimate goal is to reunify the Korean Peninsula under Seoul’s democratic leadership.

Intercepting the missile would have also denied North Korea an opportunity to advance its missile technology or, as it turned out, to learn that its missile technology actually works. And again, the United States missed an opportunity to put a stop to North Korean long-range missile tests for good.

Would shooting down the missile have been provocative? Sure. But no more so than North Korea’s decision to launch. Indeed, it would have been the only proportional response.

If we have learned anything from North Korea, it’s that sometimes it pays to be provocative. Unfortunately, that’s not President Obama’s style. The United States failed to take advantage of an opportunity to disengage from the usual kabuki dance and change the game in its favor in Northeast Asia. This is a decision the president should come to regret. The world is now a more dangerous place than it was just 24 hours ago.

Michael Mazza is a research fellow in foreign and defense policy studies at the American Enterprise Institute.