Kim Jong-il, the enigmatic North Korean leader, died on a train at 8:30 a.m. Saturday in his country. Forty-eight hours later, officials in South Korea still did not know anything about it — to say nothing of Washington, where the State Department acknowledged “press reporting” of Mr. Kim’s death well after North Korean state media had already announced it. 

For South Korean and American intelligence services to have failed to pick up any clues to this momentous development — panicked phone calls between government officials, say, or soldiers massing around Mr. Kim’s train — attests to the secretive nature of North Korea, a country not only at odds with most of the world but also sealed off from it in a way that defies spies or satellites.

Asian and American intelligence services have failed before to pick up significant developments in North Korea. Pyongyang built a sprawling plant to enrich uranium that went undetected for about a year and a half until North Korean officials showed it off in late 2010 to an American nuclear scientist. The North also helped build a complete nuclear reactor in Syria without tipping off Western intelligence.