NORTH KOREA has already provided plenty of evidence that the dynastic regime led by Kim Jong Un threatens the world and its own people. He has developed and tested nuclear weapons; built intercontinental ballistic missiles; brewed chemical weapons such as VX (a nerve agent reportedly used to kill his own half brother) and forced untold thousands of people into concentration camps. Now comes news that he is collecting the capabilities and know-how for biological weapons that could be used for germ warfare.

The Post's Joby Warrick reports that North Korea has been acquiring the essential machinery and seeking the know-how to produce large amounts of germ-warfare agents rather quickly. So far, Mr. Kim has not deployed germs into weapons. But U.S. officials are alarmed at signs that technology, barred by sanctions, has been identified within the country, while at the same time Pyongyang has exhibited an interest in genetic engineering and other biotechnology disciplines.

By its very nature, biological technology is dual-use; the machines needed to create lifesaving treatments or pesticides can also be used to create lethal agents to be delivered in wartime. A fermenter not connected to any pipes, vents or ductwork could be an innocent start to manufacturing medicines, or signify that Mr. Kim is getting ready for something darker. In the case of the largest biological weapons program ever attempted, in the Soviet Union from 1975 to 1991, much of the industrial base was created first, capable of producing anthrax by the ton, to be ready if and when the orders came to mobilize for war.

Biological weapons are tricky from a military point of view. They can be more easily hidden than nuclear missiles or conventional forces. Attacking them preemptively could risk unwanted dispersal of the germs. They are difficult to handle and store for long periods. If dispersed in the air for an attack, germs can shift with winds and weather, endangering troops and civilians, friend and foe alike. But tests in the 1950s and 1960s carried out by the United States and Britain showed that in some conditions, biological weapons can also be deadly over wide swaths of territory. The United States gave up biological weapons in 1969, and an international treaty banning them took effect in 1975. North Korea joined the treaty in 1987,but the treaty's verification requirements are weak. Despite serious obstacles at home, North Korea has demonstrated an ability to evade sanctions and scale up military industrial plants when it wants to.

If Mr. Kim is creating the foundations for a biological weapons program, it should serve as one more warning of the escalating threat he poses. Preemptive war could risk millions of casualties. But his malign intent cannot be tolerated forever. Through sanctions, diplomatic pressure and other means, the burden of Mr. Kim's despotic and reckless reign must be brought to an end.