The idea has been floated that BushCo is leaking to the public this plan of an attack on Iran (with tactical nuclear weapons, no less) as means to better enable and coax diplomatic alternatives. Yet, Kevin Drum brings up a valid point(s):

....it's the fairly obvious fact that the Bush administration is publicizing them as part of a very public PR campaign in favor of a strike against Iran. The problem is that even if this is a bluff, it's one that has a profound effect on both Iran and the American public. As James Fallows says:

By giving public warnings, the United States and Israel “create ‘excess demand’ for military action,” as our war-game leader Sam Gardiner recently put it, and constrain their own negotiating choices.

In other words, if the PR campaign is too successful, then Bush will have boxed himself in. Eventually he'll feel obligated to bomb Iran solely because he's now under pressure to make good on his threats and doesn't want to look like he's backing down. World Wars have started over less.

Who knows? A subtle and well orchestrated game of chicken might be appropriate here. But please raise your hands if you trust this crew to play a subtle and well orchestrated game of anything.