ISIS in Iraq is regrouping and carrying out more sophisticated attacks, as illustrated by assaults on numerous locations around Samarra overnight that lasted into Saturday morning.The Popular Mobilization Units, a group of mostly Shi’ite paramilitaries, said they were struck by most of the attacks and suffered casualties, around the city 120 km. north of Baghdad.The disaster began at several villages, including a checkpoint in Makishifiya (Mukashifa), according to Rudaw news, based in Iraqi Kurdistan. At least eight members of a PMU unit called the Tigris regiment died in battle against ISIS, and other PMU members from Asaib Ahl al-Haq’s brigade were also impacted. The attack was so large that numerous units scrambled to get to the affected Salahaddin governorate, to help those under attack. In recent days ISIS has carried out attacks in Iraq’s Anbar governorate. An attack took place at Jalawla and in Shura south of Mosul, and mortars were fired near Rubah on May 1. ISIS was also active near Makhmour west of Erbil, near Yathrib, Metebeja near Tikrit, Baiji and other areas. The volume of ISIS activity is clearly increasing. It appears that the number of ISIS attacks in April may have doubled from January, and the activity this month is on track to represent a dramatic increase from the fall of 2019.Numbers can’t tell us the whole story, and ISIS is much reduced from its height in 2015. Yet a study asserts that in January of this year, ISIS claimed credit for 88 attacks, while it conducted 151 in April. A map of the attack, posted online by Aaron Zelin of the Washington Institute for Near East Policy, shows the extent of these attacks, particularly north of Baghdad.The benchmark of ISIS resurgence is not just attacks. It is also how deadly they are and how complex they are. ISIS can fire mortars from a distance or carry out sniper attacks, but its decision to launch a widespread assault on paramilitaries over the weekend is a step towards more sophisticated action.Last fall ISIS was relatively diminished in its activity. Its leader Abu Bakr al-Baghdadi was killed in a US raid in Syria, and it did not take advantage of political chaos and protests in Iraq to make a comeback. However, with US-Iran tensions rising and the US-led Coalition withdrawing from around six military posts in Iraq, ISIS appears to be on the offensive. This comes amid the coronavirus crises as well and declining oil prices which poses a challenge for Iraq. The Coalition has said it carried out airstrikes in the Hamrin mountains on April 29 and that the UK hit ISIS on April 10 near Kirkuk. Australia, Canada, France and Germany also flew air support missions to aid the fight against ISIS in April.The Coalition points out that, fighting alongside Iraq and the Syrian Democratic Forces in Syria, it has helped liberate 110,000 square kilometers from ISIS and helped free 7.7 million people. The question today is whether those gains can be maintained.