To begin with, Mr. Bacevich joins other analysts who focus on what they consider the overriding difference between the two countries. Iran, despite the fiery rhetoric of its mercurial president, Mahmoud Ahmadinejad, is seen as rational and even cautious, whereas North Korea is seen as utterly unpredictable. This makes Pyongyang more dangerous, at least in the short term.
Iran certainly has internal political challenges – its economy is flagging, in part under pressure of tightened international sanctions, and the Revolutionary Guard force is playing a growing role in both economic and political affairs. It is also making substantial progress on missile development, along with its nuclear program. But it doesn't represent the imminent security threat of North Korea, say many analysts.
"It's a different kind of challenge," says Bruce Jentleson, a State Department consultant and professor of public policy and political science at Duke University in Durham, N.C. "With North Korea, it's day by day. You don't know what surprise they might present, and the concern is about a rapid escalation of military action back and forth.
"With Iran it's a different kind of time frame," he adds. "There's not as much concern that Iran will take aggressive action against us, or Israel, or anyone else in the short term."