1.   A Peruvian fighter subsequently took off and flew near the small plane and obtained the tail number, the American official said.

2.   No tail number, no large piece of the plane.

3.   Some nations require the tail number of each plane flying through its airspace, as well as the time when the aircraft enters and leaves.

4.   The official said that CIA contract personnel on a nearby American surveillance aircraft that was tracking the small plane urged the Peruvians to obtain the tail number.

5.   In some cases, fighters pull alongside an unidentified plane to call in its tail number to authorities.