Over the last several months the notion that Iran is trying to construct a land bridge or corridor of power from Tehran, via Baghdad and Damascus, to Beirut, has gained traction.The only country capable of stopping or interdicting that corridor is the United States. Although Europe and Israel and others may play a role, the power and treasure that the US possesses makes it the sole country that could stop up the various linchpins that Iran needs to complete its goal. However, the US is not going to act, not yet at least.Over the last year, several writers have explored aspects of Iran’s goal. In October 2016 Martin Chulov argued in The Guardian that “militias controlled by Tehran are poised to complete a land corridor that would give Iran huge power in the region.”In June, on the pages of The Jerusalem Post, Jonathan Spyer looked at the implications of US policy on this issue. “If the US and its allies are eclipsed in eastern Syria, the result will be the establishment of a contiguous land link from Iran, across Iraq and Syria and to Lebanon and the Israeli border.” The “land bridge” idea is now widely accepted with articles in most major Western newspapers on this issue.In the two months since June, the Iranian-backed regime in Damascus has expanded its power. On top of continuing evidence of Iranian missile factories and other weapons transfers, the regime is inching toward Deir al-Zor and Abu Kamal on the Euphrates.The problem with getting any response from Washington is that there is no evidence that there is a coherent plan to confront Iran’s land corridor. Washington is busy looking over the Iran nuclear deal, but its main focus in the region is defeating ISIS. In July, leaks and then confirmation, revealed that the CIA was ending support for some anti-Assad Syrian rebel groups. The US has also supported cease-fire deals in Syria, particularly one signed in July with Russia and Jordan.Trump’s rhetoric on Hezbollah has been tough, calling it a “menace” in late July and saying it threatens the region. The administration also announced new sanctions against Iran’s ballistic missile program. But what is missing from all this is the announcement of a real policy change on Iran to challenge it on the ground regionally. That announcement doesn’t seem to be forthcoming, even though Trump huddled with generals and national security officials on August 18 at Camp David. Myths about the US using its anti-ISIS coalition partners in Syria in a race for the Iraqi border to somehow cut off the Iranian militia land-corridor have persisted despite dwindling evidence of their practicality.In an email exchange with the coalition, Col. Joe Scrocca, director of CJTF-OIR, the US-led coalition against ISIS, stressed that “the coalition has no fight with the Syrian regime or its allies in the counter-Daesh fight.” The US emphasis is on “deconfliction” with the Syrian regime. “The deconfliction line exists to enable operations by all parties to defeat a truly evil enemy of the people of Syria, the region and the world.”The coalition “will not support any operations that are not against Daesh,” Col. Scrocca wrote. This is as clear as it gets. There is no plan to race Syrian regime troops to get to Abu Kamal on the Iraqi border.The same is true in Iraq where the US is partnered with the Iraqi government and the government forces include Iranian-backed Shia militias. The US doesn’t work with the militias, but they will fill the void left by ISIS. To imagine that US policy would change on this would require a major shift. It would mean changing Washington’s view of Baghdad as a close partner, and seeing the Syrian regime as an enemy. That isn’t realistic at the moment.Jonathan Schanzer, senior vice president for research at the Foundation for Defense of Democracies, says that the administration is frustrated in part by the policies it inherited from its predecessor. “They inherited a mess that empowered Iran. The administration is aware [of the Iranian threat],” he says. “The problem is aligning our other strategies and policies to make sure Iran doesn’t gain from the fall of ISIS.”Washington is concerned about Tehran’s rise, but it wants a policy consistent with its values, he says. That means a “light footprint” on the ground, having others contribute, and not conducting an expensive war. “So they are now in the process of trying to determine what is feasible and advisable.” They want to craft an “overarching Iran policy” but haven’t completed it yet.The question for the US and its allies, such as Kurds in Iraq and Syria, Israel, Saudi Arabia and others, is whether they are being left behind bit-by-bit on the ground with a fait accompli along the Iraqi-Syria border. Every day that goes by Iran grows stronger while US allies, most of whom don’t see eye to eye on other issues, wait for Washington to sketch out its mission.