Are talks with North Korea on or off?  Tuesday, Pyongyang said it wanted to reschedule discussions with the U.S.-led United Nations Command for Thursday.  That’s after canceling them two hours before they were to begin.  The North originally asked for the talks on Friday.  The topic is the sinking of the Cheonan, the South Korean frigate, on March 26.

North Korea’s original request raised hopes that the militant state might be turning over a new leaf.  The Washington Post, for instance, wrote this on Monday: “The meeting signals the first conciliatory step by North Korea since the Cheonan incident and suggests that Kim Jong Il’s government—in a pattern that fits its history—could again replace brinkmanship tactics with compliance.”

Perhaps we should forget about the pattern fitting history and look at the pattern this week.  Pyongyang, by pursuing its on-again-off-again tactics, is telling us it is not serious about dialogue.  The idea in Washington—during both this administration and the previous two administrations—is that talking with the North Koreans could help ease tensions and lead to their abandonment of nuclear weapons. 

American policy hasn’t worked.  While we talked to the North Koreans, at Beijing’s urging, Kim Jong Il hemmed and hawed—and used the time to detonate his first nuclear device, test a second one, and improve his long-range missiles. Oh, and I almost forgot: he also proliferated nuclear weapon technology to Iran and Syria.

Just about everyone says there is nothing that can be done about North Korea.  That’s not true.  In September 2005, the Bush administration designated one of the banks North Korea used as a “primary money laundering concern,” effectively shutting it down.  The tactic worked.  In fact, it worked so well that Pyongyang had to transfer cash in the suitcases of its traveling diplomats.  Unfortunately, Washington lifted the measures in 2007 to get the North back to talks.

On Tuesday, the Defense Department  indicated it doesn’t know whether North Korea is serious about meeting Thursday.  “I wouldn’t put any money on that,” said Pentagon spokesman Bryan Whitman. 

Instead of waiting for the North Koreans to let us know when they want to chat, here’s a better idea: Tell them they just killed 46 South Korean sailors and that, before we sit down with them, we will close down every bank they use and confiscate every money transfer they make.  We’ll give the cash back only when they surrender their last nuke and allow in the best weapons inspectors of them all: U.S. ground forces.  

Kim just committed an act of war, and the last thing we should do is talk to him.

Gordon G. Chang is the author of "Nuclear Showdown: North Korea Takes On the World." He writes a weekly column at Forbes.com.

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Gordon G. Chang is the author of "The Coming Collapse of China." He writes a weekly column at Forbes.com. Follow him on Twitter @GordonGChang.