The U.S. military is sending an aircraft carrier to the waters off South America, in the latest escalation and buildup of military forces in the region.
The early warning radars on Greenland are key to defending the U.S. against nuclear attack, but they're vulnerable to hypersonic missiles, critics warn.
Variants within the same plane model, incompatible support equipment and a lack of shared data create barriers to interoperability, a Rand report warns.