President Donald Trump confidently predicted the group's elimination when United States and allied forces took Baghuz, Syria, the last stronghold of the Islamic State's caliphate, in late March. The report's authors, though, say the group still has many fighters in Iraq and Syria who are able to move freely and carry out attacks.
Some 30,000 Islamic State foreign fighters and dependents may have survived the conflict and "will be of international concern for the foreseeable future," the analysts said. "Some may join al-Qaida or other terrorist brands that may emerge."
European governments have estimated that around 5,000 to 6,000 of their citizens had traveled to Syria and Iraq to join extremist movements, most of them signing up with the Islamic State. While many were killed or detained, up to 40% are unaccounted for.
The radicalisation of people held inside Europe's prisons "remains a critical concern," the report said, noting the first wave of returnees who had been jailed were expected to be released in the coming year.
Central Asian states said returning fighters were a worry, but they also cited concerns over terrorist threats in Afghanistan. The Trump administration is pushing forward with negotiations with the Taliban and has seemed eager to withdraw thousands of U.S. troops.
The Islamic State affiliate there has suffered military setbacks and has failed in its efforts to expand its influence across southeastern Afghanistan, the report said. Still, regional states estimated it had between 2,500 and 4,000 fighters and a "robust capability" to raise money.
Turning to al-Qaida, the report said the movement "remains resilient" despite reports this past week of the death of Hamza bin Laden, who had been groomed by his father to take over its leadership. Its affiliates were stronger than those of the Islamic State across north-central and West Africa.
The movement, the analysts said, "considers Afghanistan a continuing safe haven for its leadership, relying on its long-standing and strong relationship with the Taliban leadership."
Written by: Nick Cumming-Bruce
Photographs by: Ivor Prickett
© 2019 THE NEW YORK TIMES