Here we go again:

In his speech this month outlining the new U.S. strategy in Iraq, President Bush promised to "seek out and destroy" Iranian networks that he said were providing "advanced weaponry and training to our enemies." He is expected to strike a similar note in tonight's State of the Union speech.

For all the aggressive rhetoric, however, the Bush administration has provided scant evidence to support these claims. Nor have reporters traveling with U.S. troops seen extensive signs of Iranian involvement. During a recent sweep through a stronghold of Sunni insurgents here, a single Iranian machine gun turned up among dozens of arms caches U.S. troops uncovered. British officials have similarly accused Iran of meddling in Iraqi affairs, but say they have not found Iranian-made weapons in areas they patrol.

The lack of publicly disclosed evidence has led to questions about whether the administration is overstating its case. Some suggest Bush and his aides are pointing to Iran to deflect blame for U.S. setbacks in Iraq. Others suggest they are laying the foundation for a military strike against Iran.

Before invading Iraq, the administration warned repeatedly that Saddam Hussein was developing nuclear, chemical and biological weapons. Those statements proved wrong. The administration's charges about Iran sound uncomfortably familiar to some. "To be quite honest, I'm a little concerned that it's Iraq again," Sen. John D. Rockefeller IV, head of the Senate Intelligence Committee, said last week, referring to the administration's comments on Iran.

We've seen this movie before. As Kevin Drum writes, "we certainly shouldn't be at war [with Iran] over wildly exaggerated claims from an administration that's demonstrated conclusively that it can't be trusted with such claims."

That's the problem when you're credibility is blown: from then on you can't be trusted. They made their bed....

But more importantly, such crippled trust affects authority and endangers the country. What if Iran truly is an imminent threat? The fact we feel the need to second-guess this administration based on past transgressions potentially exposes us to more harm due to lack of action and a constant feeling of uncertainty about what's real.

During a time of war, you don't cut taxes and you don't lie and distort incessantly. Lessons learned?