Not that their being taken and held is in any way OK, nor that our government shouldn't be taking much stronger measures to get them back.
For one thing, Imadinnerjacket should be persona non grata in the US while American citizens are being held. (Should be anyway IMO)
http://www.panoramio.com/photo/25337138
It's about 2 kilometers from the Iranian border. But that is a rough 2 kilometers of steep uphill, rocky grades to a mountain ridge heavily patrolled by Iran.
The Iranian border patrol was at the grotto sightseeing and were happened upon by the three hikers. They then kidnapped the three hikers to keep from being reported to their own superiors and concocted a cover story that now has been expanded on to keep Iran from being embarrassed.