With no signs of let-up in the Iraq war, the American administration is growing uneasy about Iran’s growing intervention. With an already fragile relationship, and a stalemate on nuclear issues, the US and Iran have been staring each other down for some time now.

Last week US soldiers arrested five Iranians in Iraq, accusing them of arming and otherwise supporting the anti-US insurgency there. Now the Americans appear more willing than ever to cross the line with Iran.

Just last week President Bush ordered an additional 21,500 troops to the region, along with the an extra carrier strike group and Patriot anti-missile batteries – “a clear signal that [Bush] is giving himself the option of a military strike to halt Iran's suspected development of nuclear weapons.”

Of course, once you get into a pissing contest with an already bellicose country striving for regional dominance, there is no backing down. The United States doesn’t want to appear soft in dealing with Iran. But once again Bush is painting himself into a corner by referring at least, if not immediately resorting, to a military solution.

The rules of escalation are clear and well known. Iran is feeling more and more threatened, with thousands of American soldiers just over the border, and Bush’s less than subtle language.

Iran is far from innocent in this ordeal. Its insistence on nuclear development (which, if it was purely non-military should not be afraid of IAEA inspections), and manipulation of the Iraq insurgency have served as reciprocally belligerent affronts against the Americans.

In this kind of diplomatically fragile atmosphere, it is what is not being said that matters most. The Americans refusal to rule out crossing the Iranian border, regardless of all the caveats of recognized risk, is a clear sign to the Iranians to prepare for war.