ISIS Is Preparing for Another War With 30,000 Fighters in Iraq and Syria: U.N. Report

After the Islamic State militant group's so-called caliphate crumbled last year, world powers hailed the defeat of the Sunni extremists across Iraq and Syria. Reports suggested remaining fighters were confined to a thin strip of desert between the two countries, with the noose tightening around the group's neck.

But far from being destroyed, 30,000 committed Islamic State (ISIS) fighters are preparing for new wars across the globe, waiting for their chance to launch new offensives and re-establish the short-lived state, suggests a new United Nations report.

According to The Associated Press, the report to the U.N. Security Council warns that the threat of ISIS activity is growing, as is that of Al-Qaeda, which has rebuilt and and refocused since the death of leader Osama bin Laden in 2011.

An ISIS fighter in the city of Mosul, Iraq, on June 23, 2014. The group's so-called caliphate has collapsed, but tens of thousands of fighters remain spread across the region. REUTERS/Stringer

The authors estimate total ISIS strength at between 20,000 and 30,000 fighters in Iraq and Syria, citing analysis from unnamed governments. These forces include "a significant component of the many thousands of active foreign terrorist fighters," it says.

ISIS suffered terrible losses as it was driven out of territory seized in both countries from 2014 onward. The caliphate was home to more than 10 million people at its peak, stretching from just north of the Iraqi capital Baghdad to the outskirts of Aleppo in Syria.

Despite the casualties, diehard militants remain committed to the fight. Some remain active on the battlefield, while many others are "hiding out in sympathetic communities and urban areas" as the group transitions from a nascent state to a guerilla warfare network. This process is more advanced in Iraq, the report explains, as ISIS retains pockets of control in Syria.

Affiliate ISIS groups have been formed all over the world, from Nigeria to the Philippines. The geographical spread of ISIS fighters and allied groups necessitates delegation by leader Abu Bakr al-Baghdadi. Despite this decentralization and reports he has been seriously injured by airstrikes, Baghdadi "remains in authority," the report says.

As the caliphate crumbled, the home nations of foreign fighters feared they would return and wreak havoc, especially in Europe. Though there have been some notable attacks of this nature, the rate of terror incidents in Europe has remained low. Nonetheless, the report says governments "assess that the underlying drivers of terrorism are all present and perhaps more acute than ever before," meaning future attacks remain likely.

A resurgent Al-Qaeda is also a threat. Though eclipsed by ISIS in terms of notoriety and influence, at least in recent years, the network "continues to show resilience" and in some areas still surpasses ISIS as the dominant jihadi force. The report suggests Al-Qaeda leaders operating from Iran are working closely with leader Ayman al-Zawahri, "projecting his authority more effectively than he could previously."

Ongoing instability and conflicts across the globe allow both ISIS and Al-Qaeda to operate relatively freely, attract recruits and grow their influence. As many as 4,000 ISIS fighters could be in Libya, despite Western airstrikes driving the group from the coastal city of Sirte. Another 1,000 have pledged allegiance to Baghdadi in Egypt's Sinai Peninsula, and continue operations against security forces.

The ruins of Mosul, Iraq, on March 21. ISIS's former caliphate has been destroyed, but tens of thousands of its fighters remain a threat. REUTERS/Alaa al-Marjani

Both groups are fighting in West Africa, where a multinational force is battling jihadis in the Sahel, Al-Qaeda in the Islamic Maghreb being the most dangerous foe. An al-Qaeda affiliate also dominates East Africa in the shape of Al-Shabab, which continues to fight the Somali government and has been the target of several American special forces operations.

War in Yemen has given Al-Qaeda an opportunity to strengthen significantly. A few hundred ISIS fighters are also believed to be in the country, but al-Qaeda in the Arabian Peninsula is still the most influential jihadi group in the region. The organization has used this base to plan foreign attacks, most notably the Charlie Hebdo shooting in Paris in 2015.

Southeast Asia is a big growth area for both groups. Islamist insurgencies have been bubbling away in the south of Thailand and the Philippines for many years, and Al-Qaeda and ISIS are both attempting to exploit existing networks there.

Last year, a Filipino ISIS affiliate group managed to capture the city of Marawi and hold it against government forces for five months. Though the city was retaken and many ISIS members killed, the U.N. report warns the group's local affiliates "are cash rich and growing in membership." The violence has also spread to Indonesia, the world's most populous Muslim nation. Several bombings claimed by ISIS indicate the group is trying to put down roots in the country.