For years, countries including the United States have failed to take serious steps to rein in North Korea's erratic, dangerous regime.
Things have drifted badly. North Korea has taken advantage by boosting its nuclear-weapons and missile capabilities.
But its test firing of a ballistic missile last weekend changed the situation in a big way. The test triggered international alarm that North Korea is nearing the point when it can develop and field nuclear-equipped long-range missiles.
South Korea's government responded by taking an action it had declined to do for years: It has begun formal discussions about hosting a U.S.-controlled high-altitude missile defense system.
Seoul had long held off from that action, bowing to fierce opposition from China, whose nuclear threat would be undercut as a result. South Korea's willingness to host such technology now is a dramatic sign of how greatly things have changed as a result of the North Korean missile test.
North Korea has added to worries by restarting a military-related plutonium reactor and pursuing creation of a hydrogen bomb.
Another needed step is for the U.S. to pursue Iran-style economic sanctions against North Korea. China protests that such penalties would pinch Chinese companies, but the security situation has worsened to such a degree that such sanctions are fully warranted.
The blame for this situation falls squarely on North Korea, as well as on the failures of China's diplomacy. Beijing launched a last-ditch effort to prevent the missile test, but the gesture was defiantly rejected by North Korea's leader, Kim Jong Un.
Leaders in North Korea and China need to understand that actions have consequences. It's time for strong, effective action to counter the North Korean threat.
It's time for strong, effective action to counter the North Korean threat.