An Iranian engineer claims his country actually hijacked our unmanned drone instead of it simply being lost as claimed by the CIA.

In an exclusive interview with The Christian Science Monitor an engineer currently working on reverse engineering the craft has gone on the record and claimed the CIA's bat-winged RQ-170 Sentinel lost last week was stolen.

Using a system of jamming and changing the GPS signals received by the craft the Iranians were able to make the craft report it was landing where the CIA intended.  Instead it landed inside the country, intact and only slightly damaged.

GPS signals are relatively weak signals especially compared to intentional ground based jamming.

For more see this source article.