China had protested what it called "close-in reconnaissance" of Chinese territory by the U.S. military in the past.

The EPA measures regional air quality index (AQI) by how hazardous it is to the general public. Discover the AQI in your city by searching below.

Its predecessor, the Continental Air Defense Command ... Here's what to know as the tracker mapped out Santa's journey. From his starting point at the North Pole, the map shows Santa headed ...

the Continental Air Defense Command, handled the project for three years before NORAD took over. Here's what to know as the tracker mapped out Santa's journey. NORAD updated its map in real time ...