One of the challenges facing UN weapons inspectors in Syria is how to gain access to areas controlled by rebels.
Opposition fighters are deeply divided, and some of them are linked to al-Qaeda. Christoph Reuter, a journalist with Der Spiegel, has been reporting from Atmeh, near the Turkish border, and describes the town, dominated by Islamists, as a sort of "disneyland for jihadists."
Reuter said the town has affordable housing, Internet cafes and even clothing shops specializing in jihadi outfits.
"Together, (it) makes a kind of club for jihadis who come to Syria not necessarily to fight, but to tell all their friends back home that they are a jihadi in Syria now," he said.
The largest number of jihadis in Atmeh, he said, are Tunisians. Other cities have Saudis, Chechens, Egyptians, Moroccans and even Indonesia. The Syria rebels have become a truly international coalition.
At the airports in Turkey, the primary transit points for these fighters, Reuter said, you stand in line with an assortment of jihadis.
"We don't have precise numbers, but probably 30% to 40% go to fight. And maybe a third come to Syria and stay inland around Atmeh," he said. "They have no intention of going anywhere. It's really surreal."
This overwhelming presence of jihadi-linked fighters has western governments worried. And even rebel groups, Reuter said, seem a little uneasy. But there's no question they're glad for the help.
"They all give you the same answer. They say 'We ask everybody for help. We ask Americans for help. We ask the Saudis for help. We ask Europe for help. The only people who came to help are jihadis from all over the Sunni world,'" Reuter said.
Still, if the Syrian rebels can topple Bashar al-Assad's government, they'll be forced then to deal with kicking out the foreign jihadis, Reuter added.