WASHINGTON (AP) - Homeland Security Secretary Janet Napolitano says new security rules are in place banning all cargo from Yemen and Somalia and prohibiting the transport of printer toner and ink cartridges weighing more than one pound on passenger flights.

The new rules come after counterterrorism officials thwarted a terror plot last month that shipped bombs hidden inside printers in packages bound on aircraft from Yemen to the U.S.

Immediately after officials learned of the plot, the U.S. ordered a temporary ban on all cargo from Yemen. Monday's announcement extends that ban to Somalia, where intelligence officials believe terrorists are actively plotting attacks against the U.S.