ABC News reports that according to U.S. defense sources, incontrovertible proof now exists of Iran's material assistance to Iraqi Shiite forces:

U.S. officials say they have found smoking-gun evidence of Iranian support for terrorists in Iraq: brand-new weapons fresh from Iranian factories. According to a senior defense official, coalition forces have recently seized Iranian-made weapons and munitions that bear manufacturing dates in 2006.

Iranian-made munitions found in Iraq include advanced IEDs designed to pierce armor and anti-tank weapons. U.S. intelligence believes the weapons have been supplied to Iraq's growing Shia militias from Iran's Islamic Revolutionary Guards Corps, which is also believed to be training Iraqi militia fighters in Iran.

This has been known or suspected for a while, of course. The 2006 munitions may have just been captured, or this news may be part of an effort to influence public reaction to the soon-to-be-released Baker-Hamilton report. If we're going to "talk to Iran," as the Baker commission is expected to recommend, what, exactly, are we going to tell Ahmadinejad that will convince him that instead of fomenting and enabling violence in Iraq, he should help us stop it?

It's certainly a question we'll have in mind when we read the commission's report.

PAUL adds: So this means war, right?

SCOTT adds: Michael Ledeen writes in response to Paul's question:

The really big news in that story is that, for the first time (I think), American officials branded the Iranian regime as responsible for the weapons traffic. Up until now, they have always given the mullahs some wiggle room, you know, maybe 'rogue elements' are at work. But not this time.

Yes, it's war. A bit lopsided, to be sure; they've been attacking and killing Americans for 27 years. We keep offering goodies. It seems our commanders in the field have decided to blow the whistle on our feckless politicos.

JOHN responds: I wonder whether our commanders have decided to blow the whistle on the Baker-Hamilton commission, specifically.