Obama's Cone of Silence

The BBC has an article about the mobile security setup that the US president uses when he travels.

Designed to withstand eavesdropping, phone tapping and computer hacking, Sensitive Compartmented Information Facilities - also known as SCIFs - are protected areas where classified conversations can be held.
They can be permanent enclosures within a building, or mobile areas set up when a world leader is on the move, to allow them to view sensitive documents or have secret conversations without any outsiders listening or hacking in.