What's the most logical way to complete this passage?

(CNN)Night had just fallen when heavily armed Belgian commandos approached a residence on the Rue des Collines in Verviers, a sleepy town in eastern Belgium. They knew the three men inside -- all suspected to be hardened Belgian ISIS veterans who had returned from fighting in Syria -- were likely to be armed and dangerous because they had put them under 24-hour surveillance for several weeks, according to a senior Belgian counterterrorism official. Wiretaps of phone conversations and listening devices indicated the cell members -- who had been under observation for just under two months and were all from in and around the Molenbeek district of Brussels -- were in the final stages of preparing a major terrorist attack in Belgium, the official told CNN.

Belgian investigators are skeptical of that claim and have no evidence to suggest he was able to reach
Belgian.