Phixius

Answer: There were counter attacks in Washington and New York along with the L.A. squadron. Only the L.A. scene was shown because Will Smith is a main character. The guy with the headset on in the command center that was coordinating the attack alongside the general and the president mentioned that the Washington, and New York squadrons were locked on as well as with L.A. As you could imagine their efforts were futile, along with the one shown with Will Smith, and were only worth mentioning. Also when they reached Area 51, the General told the secretary of defense that they should have told them about this place before they launched an attack that cost them the lives of hundreds of American pilots. The L.A. battle seemed to only show maybe 4 or 5 dozen aircraft, not hundreds.

Answer: Most likely because the military "deciders" didn't know what to expect from the aliens and the ship Will Smith's unit attacked was in the least populated area, thus minimizing any potential civilian casualties. They were testing the waters, so to speak, before committing too many resources on a tactic that may prove futile.

Phixius ★