The vote demonstrates once again that the differences between the White House and the Democrats are purely tactical. What unites all factions of the American political establishment is their defence of the strategic and economic interests of US imperialism in the Middle East. None of them has any principled opposition to a US military attack on Iran, if it would further American domination in this key region.

In his speech, Lieberman pointed to the underlying US strategic interests involved. “One of them was to prevent Iran from dominating parts of Iraq. Another was to preserve our credibility in the region... that is important to us in so many ways. In the most direct way... we continue to depend too much on oil and gas that comes from the Middle East so we have an interest in keeping it stable,” he declared.

While it mandates no action beyond regular reports to Congress, the Lieberman amendment effectively endorses the Bush administration’s propaganda against Iran. For months, the White House and the Pentagon have maintained a steady drumbeat: the Iranian Revolutionary Guards are training, financing and supplying arms, including deadly armour-piercing devices, to militias that are killing US troops.

No concrete evidence has been provided beyond the occasional display of Iranian manufactured arms and statements purportedly made by militia members locked away in US detention. Iranian officials have repeatedly dismissed the allegations. Nevertheless the accusations have steadily escalated. On July 2, US military spokesman Brigadier General Kevin Bergner for the first time accused the highest levels of the Iranian government of direct involvement in attacks on US forces, specifically the killing of five American troops in Karbala in January.

The outrage and righteous indignation of Lieberman and others over alleged Iranian “meddling” in Iraq is staggering for its hypocrisy and arrogance. The Bush administration has 160,000 troops inside Iraq waging a criminal neo-colonial war for the domination of the country’s resources. It has endorsed covert operations inside Iran aimed at destabilising the regime and has repeatedly declared that in dealing with Tehran all options are on the table, including the military one.

The amendment was only passed 97-0 after Lieberman agreed to include a proviso that nothing in the measure “shall be construed to authorise or otherwise speak to the use of armed forces against Iran.” But this purely legalistic caveat will not prevent the Bush administration from taking military action against Iran and could well be exploited to justify a US attack in the name of “self-defence”. In fact, US accusations of Iranian support for Iraqi militias have become increasingly shrill as it has become clear that the UN Security Council is unlikely to authorise the use of military force over a second pretext—Iran’s nuclear programs.

Lieberman, an unapologetic supporter of the Iraq occupation, makes no bones about his stance. In a comment in the Wall Street Journal last Friday, he bluntly accused Iran of waging a “proxy war” against the US not only in Iraq, but also in Afghanistan, Palestine and Lebanon. While calling for diplomatic efforts, he declared: “The fact is, any diplomacy with Iran is more likely to be effective if it is backed by a credible threat of force—credible in the dual sense that we mean it, and the Iranians believe it... It is time to restore that fear [of US retaliation], and to inject greater doubt into the decision-making of the Iranian leaders about the risks they are now running.”

“A credible threat of force” can only mean one thing: the willingness to attack Iranian military units and installations allegedly involved in Iraq. As Lieberman told CBS’s “Face the Nation” last month, the US government must “be prepared to take aggressive military action against the Iranians”. The Pentagon has already provocatively stationed two aircraft carrier battle groups in the Persian Gulf and reinforced the military capability of US regional allies. A third aircraft carrier group led by the USS Enterprise is currently heading towards the Middle East—reportedly to replace the existing two.

Whether or not the Bush administration will authorise military strikes on Iran remains unclear. What attitude the US will adopt towards Iran is part of the debate raging in ruling circles, including in the White House, over the catastrophe in Iraq. Lieberman speaks for a considerable layer of the American political establishment that advocates the unrestrained use of US military might to pursue its strategic and economic ambitions. Far from being held back by the Iraqi quagmire, the advocates of “regime change” in Tehran propose to extend the war into a broad regional conflict against Iran and its “proxies” throughout the Middle East.

At stake is the control of the region’s oil and gas. Any back down or compromise over Iran would leave America’s Asian and European economic rivals holding all of the stakes in that country’s resources. Likewise any US retreat from Iraq would leave the field open for other powers to fill the vacuum. The alternative is a macabre and reckless gamble that a war against Iran would establish US domination over the region as a whole.

What was significant about Wednesday’s vote was the willingness of the entire US Senate to endorse the pretext for a new war. It is a clear signal that the Democrats would rapidly fall into line with any military adventure in Iran, despite the overwhelming antiwar sentiment among the American population as a whole.