Through the rubbish-strewn streets, past the scorched wrecks of cars, into a courtyard peppered with empty plastic water bottles, and suddenly you are inside their dark squalid room. About 30 African migrant hopefuls, sat crushed knee-to-knee, wrestling with their new fate as prisoners of Libya's immigration police. Eugene speaks first, tearfully talking of his brother and father, killed by a bomb in Nigeria, planted by Daesh (so-called IS) affiliate Boko Haram. "Today bomb blast, tomorrow bomb blast," he sobs of his decision to leave Nigeria and let smugglers help him across the dusty African route to Libya. "Let me go out, let me travel out. Here in Libya there is no peace. We don't have peace." The men were caught moments earlier when police raided the tiny seafront building where they were herded, before being shipped across the Mediterranean. They are part of an explosion in migrants seeking to use the Libyan route to Europe — an estimated 100,000 so far this year as the Turkish shores close up — but also now caught up in a new threat. Libyan officials and a smuggler told us that Daesh militants — who have quietly expanded their control of Libya to about a tenth of its coastline — have tried to use this traffic in human misery to move their fighters to Europe. A smuggler told CNN about a month ago that he was asked by a "devout man" he knew to be Daesh, to smuggle 25 militants to Europe by boat for $40,000. He refused but added he had in the past fortnight heard of a boat of 40 Daesh who had set sail from their stronghold of Sirte with a smuggler. Bad weather turned them back, yet they tried again. He didn't know of their fate, but added that smugglers had no moral issues transporting Daesh. They "are only interested in smuggling. Daesh, anyone. They don't care. Melon or water melon.... Money only matters." The trade had become noticeable in the past two months, the smuggler told us. Some militants are shaving their beards before they leave, and traveling with families — specially assembled just for the journey — to arouse less suspicion. We ventured out to sea with the only line of defense Libya can provide Europe against this threat — its coast guard. They have just six small inflatable boats to patrol the coastline of the capital Tripoli, yet told us only the one we were traveling in was actually in service. The sense of the challenge ahead is palpable. — The writer is CNN's senior international correspondent