Dutch:
http://www.nu.nl/binnenland/4273785/...-nijmegen.html
http://www.nrc.nl/next/2016/06/06/ne...eldorf-1625633
French:
http://www.lemonde.fr/europe/article...2096_3214.html
English - lacking some new info:
http://www.thelocal.de/20160602/isis...arrests-france
Translation from the Dutch links:
A Syrian man called Saleh A. reported himself to the French police on February 1st, saying a sleeper cell consisting of 20 men was waiting for a call to arms from ISIS, stating they'd be ready to act within 24 hours of being called up. The sleeper cell was spread out between refugee camps in Nijmegen and Düsseldorf. The German police arrested three Syrian men last Thursday, using information released by Saleh A.
They had planned for two suicide bombers to detonate explosives along a main thoroughfare near the area’s subway station, a popular area in Düsseldorf, while other armed attackers were to carry out further killings with weapons and more explosives.
Saleh and two of the arrested men traveled to Europe via Turkey (2014) and the Balkans (2015). Initially, Saleh A was supposed to deliver a video to the Vatican showing that the kidnapped priest Paolo Dall’Oglio was still alive. For some reason this didn't happen, and Saleh A decided to report himself after being tired of roaming from refugee camp to refugee camp for two years (calling himself an ex-jihadist).
Police are still investigating his motive and claims, but seeing as three related Syrians got arrested already, it seems fairly accurate.
No arrests have taken place yet in The Netherlands, and the Dutch Public Prosecution Service can't comment on "ongoing investigations".
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So, that still leaves us with at least 16 (known) sleeper agents most likely spread out between The Netherlands and Germany, possibly other Northern European countries too. Considering some members of this cell already got arrested, how unlikely does it seem that the remaining ones will strike (soon)?