ROME — The Bari-Palese CARA Refugee Reception Center in Italy’s southern province of Puglia was built to host 850 refugees. These days, it’s overflowing with 1,389—mostly men from Nigeria, Afghanistan, Pakistan, and Bangladesh who wait behind high walls and spirals of barbed wire for their political-asylum applications to be heard.

The center is a hotbed of discontent, and most of the men who stay there would rather be just about anywhere else. In 2013, a Kurdish refugee was killed there in a violent riot that started as a protest against maltreatment. Since then, the camp gates are left open so the refugees and migrants can come and go as they please.

Early Tuesday, Italian anti-mafia police (who are also in charge of anti-terrorism activities in the country) entered the camp and arrested Hakim Nasiri, a 23-year-old from Afghanistan, on international terrorism charges. He had been granted provisional political asylum on May 5, despite the fact that undercover detectives posing as refugees inside the camp had been trailing his suspicious movements since December.

Among the treasure trove of selfies found on his cellphone was one with the mayor of Bari, Antonio Decaro, taken at a rally in support of integrating Italy’s growing immigrant communities. Other photos confiscated by police show Nasiri brandishing semi-automatic weapons in unidentifiable gun shops.

At the same time across town, police also arrested Gulistan Ahmadzai, 29, also from Afghanistan, on charges he abetted illegal immigration specifically related to the alleged recruitment of jihadi fighters who he helped bring into Europe as well as a connection to “Islamic fundamentalists associated with attacks in Paris and Belgium,” according to the arrest warrant issued by the anti-mafia police. On his computer, police said they found propaganda material for “jihadi fighters sympathetic to the Islamic State” and instruction manuals for building explosives. Also according to the arrest warrant, he was said to represent the Islamic Emirate of Afghanistan, an ISIS splinter group that reportedly broke off from the Taliban.

Ahmadzai had been given full political asylum in September 2011 and may have helped Nasiri reach Italy. Police said three other men— Ahmadzai Qari Khesta, Ahmadzai Surgul, and Amjad Zulfiqar—are affiliated with the alleged terrorist cell, and are still at large.

Local investigators say they first discovered the network last December when they stopped four foreigners who were capturing video of a large commercial center in Bari with a cellphone. They sequestered the phone, which they said led them to the rest of the suspects arrested Tuesday. Several of the suspects had apparently taken low-cost flights from Bari to Paris in December 2015. They are also accused of playing an integral role in a human-trafficking ring that facilitates the illegal travel of migrants from southern Italy to Calais, France, and Hungary.

Roberto Rossi, Puglia’s anti-mafia district director, said the men in custody had photos and videos on their cellphones of the Coliseum and Circus Maximus in Rome and the tourist cruise ship port and a large shopping center in Bari that were of “no tourist value,” he said. “They were inspections by the cell to carry out attacks.”

The men also had a number of photos and videos of hotels, shopping centers, and apartment blocks in suburban London, including the Sunborn Yacht Hotel, which is permanently docked in the East London Royal Docks, as well as the South Quay Foot drawbridge to Canary Wharf and the entrances of the Premier Inn London Stratford and the Ibis Styles London Excel, which are uninspiring moderate-for-London hotels in the area.

“This was an organization planning an attack through the preliminary inspection of the locations, including photographic and video documentation,” Rossi said. “They were clearly planning terrorist attacks at airports, ports, law-enforcement buildings, commercial centers, hotels, as well as other unspecified terrorist attacks in Italy and England."

Rossi said the men also had images of weapons and “star” Taliban militants as well as audio files of “prayers and proselytization chants relating to the indoctrination of radical Islam.” He said the men also had collected video tributes to apparent relatives and friends who were being held at the U.S. prison in Guantanamo Bay, as well as a computer in Ahmadzai’s apartment with radical-Islam recruitment propaganda and manuals for building explosives.

Before the arrests, European counterterrorism forces had come under scrutiny by aid agencies for effectively “terrorist-hunting” in refugee camps in Italy and Greece. There has been a fierce debate about whether or not terrorists could come into Italy and Greece through the migrant trails, but aid workers instead warn that most refugees are escaping the same terrorists Westererns fear. Nearly 29,000 migrants and refugees have arrived in Italy from Libya since the beginning of 2016, compared to more than 155,000 who have arrived in Greece via Turkey, though there have been no Greek arrivals documented yet in May, after a contentious agreement that includes sending refugees back to Turkey.

Out of fears that terrorists have infiltrated the refugees, Europol said it recently sent some 150 agents into the camps in Italy and Greece to screen suspect refugees who might be sympathetic to ISIS. It is unclear how many others were sent in on undercover missions to pose as refugees and keep an ear to the ground to find suspects like those arrested Tuesday.

Over the weekend, Italian anti-terrorism forces netted a man from Slovenia who was allegedly combing refugee centers in Northern Italy for recruits among those stuck in asylum limbo. Italy’s interior minister heralded the arrest as proof that Italy’s anti-terrorism forces are keeping the territory safe. Over the last 12 months, he said, Italy has expelled more than 60 non-Italian suspected Islamic extremists and has nearly 100 Italians sympathetic to ISIS under constant surveillance.

The arrests may be a feather in the cap of anti-terrorism forces in Italy, who can now claim with proof that their vigilance is paying off. But it has done little to calm fears that terrorists are lurking among the legitimate refugees.