With Washington and Tehran nearing the brink of war, the rest of the world looks on nervously. But which U.S. allies would actively back the United States should a full-scale war break out?

More supportive would most likely be some of the Gulf monarchies such as Saudi Arabia and Bahrain. Many of these countries house U.S. bases and share the Trump Administration’s hostility to Iran. Several of them supported the U.S.’s withdrawal from the Iran nuclear deal, and Saudi Arabia is already engaged in fighting Iranian-backed Houthi fighters in Yemen. Though the Gulf monarchies possess significant levels of military hardware, they would most likely primarily serve as a launchpad for U.S. attacks on Iran rather than as active participants.

However, the Gulf is by no means unanimous on this point. A notable exception is Oman, which is generally the most peaceful country on the Arabian Peninsula. Located across from Iran along the Straits of Hormuz, the sultanate served as a backchannel between the U.S. and Iran in the leadup to open and direct talks between the two. Additionally, Oman has been pushing for years for Iranian oil imports as well as an underwater gas pipeline connecting the two countries.

A more recent change in the Gulf has been Qatar. Though initially part of the anti-Iran axis, the oil-rich state has been the target of a multi-year campaign led by Saudi Arabia and others to isolate it diplomatically and economically. Alleged plans by some of the Gulf Cooperation Council countries to invade Qatar, which houses 10,000 U.S. servicemen at the Al Udeid Air Base, might explain why Qatar’s foreign minister traveled to meet his Iranian counterpart a day after the assassination of Qassem Soleimani.

Perhaps the most anti-Iranian leader in the world is Israel’s Benjamin Netanyahu, who for decades has led the pro-war camp as well as having sought to bring his country closer to some of the Gulf states. While Israel has attacked Iranian forces in Syria and possesses the capability to strike Hezbollah in Lebanon, anti-Israel sentiments throughout the region and the relatively small size of its military, is likely to preclude any significant Israeli participation in a ground offensive. If anything, its entry may unite the different segments of Iran’s population. It was for this reason that the George H.W. Bush Administration called for Israel not to retaliate against Iraqi Scud missile attacks during the Persian Gulf War.

In general, these countries have achieved tactical successes, but strategic failures in recent wars. Israel’s war in Lebanon in 2006 resulted in significant devastation and an unbalanced death toll, yet Israel was unable to inflict any long term injuries on Hassan Nasrallah’s forces. Likewise, the Saudi-led war in Yemen is approaching its fifth year with little to show for it.

The U.S. should not expect to receive any support — even symbolic — from Iraq. Unannounced airstrikes, as well as the unpermitted deployment of U.S. troops from Syria, has left the United States with virtually no friends in Baghdad whether Sunni or Shi’ite.

It is doubtful that Turkey would support the U.S. in a war against its neighbor. Ankara will not want to receive any more refugees from a country with a population four and a half times greater than that of Syria, which itself has already produced roughly four million refugees. In addition to not wanting a third Middle Eastern war-torn country along its border, a collapsed Iranian state will likely prove to be a fertile breeding ground for yet another active Kurdish movement. Should that be the case, the U.S. and Turkey could easily end up on the opposite side of a civil war.

Similar concerns to those of Turkey’s would likely crop up in Islamabad as well. With Pakistan, which has been an active partner in the Global War on Terror, already neighboring a U.S.-invaded state to its west and facing continued tensions with potentially nuclear consequences to its east, the country would have little to gain from yet another conflict in the region. Additionally, while not wanting to alienate its long-time ally Saudi Arabia, Pakistan might face repercussions at home should it intervene in a potential conflict, with ethnic and religious tensions unleashed by a war surely spilling over.

In Europe, an Iran-U.S. war will contribute to further divisions on the continent. Yet, such a schism would not be inherently rooted in the issue of Iran but rather on the question of support for the United States. France and Germany, which have long sought to salvage the Iran nuclear deal, along with the European Union will continue their opposition to a hot war — especially with the desire to stave off another refugee crisis. Other European countries, especially those that constituted what former Defense Secretary Donald Rumsfeld termed “New Europe”, will wish to stand by the United States even if they are materially non-significant, perhaps at most only deploying a few hundred troops or support staff, if not mere dozens. A state like Poland, which has been pushing for the establishment for a U.S. military base in the country, can be expected to toe the U.S. line for its own interest.

Yet, such support will most likely be very short-lived if it even comes to fruition in the first place. Many of the countries that supported the U.S. in its invasion of Iraq in 2003, such as Spain and Italy, had populations that were massively opposed to their own nations’ participation. Subsequent elections in Europe were partially defined by such opposition and the pledge to bring troops home.

Rhetorical support can be expected from far away countries likewise seeking to align themselves more closely with the United States. Brazil’s Jair Bolsonaro, for example, has sought to differentiate himself from former President Lula de Silva, who was well known for having maintained friendly ties with the Islamic Republic. Rhetorical support might prove to be a validating factor for the Trump Administration domestically but would not translate to contribution in a war effort.

A fundamental difference between the current situation with Iran and the one with Iraq in 2003 has to do with a United Nations Security Council (UNSC) resolution. While one authorizing the invasion of Iraq did not exist in 2003, one was later given in May that paved the way for the occupation. It was under the auspices of a UNSC resolution that countries like the Netherlands sent in their troops. As such, the U.S. might not have many active participants in case of an invasion.

With recent memories of Iraq, Libya and Syria, UNSC permanent member states Russia and China and even France are unlikely to grant any authorizations. This will be especially true for as long as the Iranian government is able to exist. With considerably more support from foreign powers as well as a strong military, the Iranian military can be expected to put up considerable resistance, especially if the U.S. does not deploy hundreds of thousands of troops.

The road ahead can be a lonely one for U.S. troops marching on the ground.