In defiance of worldwide warnings, President Trump recognized Jerusalem as the capital of Israel. The announcement prompted an almost universal diplomatic backlash and angered countries with significant Muslim populations. Most of the international community does not recognize Jerusalem as Israel's capital until the issue is resolved through negotiations with the Palestinians. It’s not diplomatic protests only; the decision may spark a large-scale military conflict to dwarf the ongoing war against Islamic State and the conflict in Syria.

Akram al-Kaabi, the leader of the Iran-backed Harakat Hezbollah al-Nujaba Shia group, said that President Trump’s decision to recognize Jerusalem as the capital of Israel was a “legitimate reason” to attack US forces in Iraq. With about 10,000 fighters, Nujaba is one of the most important militias in the country. Made up of Iraqis, it is loyal to Iran. The group is part of the Iraqi Popular Mobilization Forces (PMF), a mostly Iranian-backed coalition of Shi‘ite militias that played a role in combating Islamic State. The PMF is government sanctioned and formally reports to Prime Minister Haider al-Abadi’s office. Nujaba has deployed forces in Syria in support of the Syrian government.

In November, Republican Senator Ted Poe introduced a bill to the US Congress, suggesting that the US government consider the Iraqi armed groups of Harakat Hezbollah al-Nujaba (Nujaba) and Asa’ib Ahl Al-Haq (AAH) as two proxies of the Iranian Revolutionary Guard Corps (IRGC). United States has more than 5,200 troops deployed to Iraq. Nujaba’s leader Akram al-Kaabi was earlier sanctioned by the Treasury Department “for threatening the peace and stability of Iraq.”

Former Prime Minister of Iraq Nouri al-Maliki, a Shia Muslim, called Trump’s announcement a “declaration of war.” Powerful Shiite cleric Moqtada al-Sadr, who heads his own militia, demanded the closure of the American embassy in Baghdad and warned that "we can reach Israel through Syria”. At the same time, the US president’s decision is by and large supported by Iraqi Kurds outraged about the campaign in support of Jerusalem and Palestinian rights while ignoring Kurdish rights.

It’s worth noting that it was not the first threat to strike US forces in the region, such warnings have been made before. On November 1, 2017, the Lebanese daily Al-Akhbar published an article quoting "Iraqi resistance" elements declaring their intent to attack US troops in Iraq. The PMU, made up of about 40 militias, were “preparing to reorganizing our ranks and preparing for the great conflict with the Americans.” Most, if not all, PMU factions perceive the US military presence in Iraq as an occupation.

President Trump granted US commanders the authority to order attacks in countries with American military presence on January 29. The United States is already involved in places such as Syria and the Persian Gulf where confrontation with Iran is looming. It greatly increases the risk of igniting a conflict in case of an accident.

If shooting starts, the US will fight the enemy, which is formally an element of the Iraqi regular army – a US ally. Billions of dollars in aid and advanced weaponry have gone to rebuilding the Iraqi armed forces over the last decade. The question is – will the US be at war with Iraq? The Iraqi government is hardly in a position to spoil the relations with the PMU and risk an internal unrest.

Will the clashes automatically lead to combat actions between the U.S and Iran spreading across the region? The Shia units have a large presence in Syria. If a conflict is sparked, it is likely to spread to Syria, with the US boosting its military presence in the country to negatively affect the Russia-initiated prospects for peace process. Armed opposition forces will seize the opportunities resulting from the US – Shia conflict.

With the Kurds supporting America on the Jerusalem issue, will the Kurdish peshmerga (paramilitary units) could be involved in fighting against Shiite formations. If the US forces are reinforced to fight the PMU, the temptation may be irresistible to recapture Kirkuk and the oil fields and make them a part of Kurdistan again.

Once the conflict will be a consequence of the recognition of Jerusalem as Israel’s capital, the PMU fighters will enjoy public support in Arab countries.

Another consequence – the fighting is likely to be followed by clashes between Israeli forces and Shia units in Syria. This may involve the Russia-supported Syrian government troops. The probability is great that, sooner or later, the situation will evolve to combat actions between US-Iran, Israel-Iran conflicts.

The fighting will spread to Lebanon where Shia Hezbollah enjoys great influence.

What is to be expected in the near future? The US will have to move increase its military presence in Iraq and Syria. American naval forces will move to take positions in the Persian Gulf and the Mediterranean. The US is likely to avoid further aggravation of the situation in the Korean Peninsula not to be involved in two conflicts simultaneously.

The risk of a major war between the US and Iran will evolve according to certain scenarios and will have global consequences. There is a big chance that Iran will lead the Muslim world movement against the US and Israel provoked by the recognition of Jerusalem.

Actually, the recognition is not what it is at first glance if one goes to the bottom of it. But it is highly provocative and untimely. The decision has a lot of cons and few of pros and it is unlikely to benefit the United States but it is fraught with headaches. You reap what you sow. The US military is facing a real threat in Iraq. If it sparks, the consequences will be dire.