Dulce Base (The Dulce Files, #1)

The U.S. government has allowed the Grays, a race of extra-terrestrials from the Zeta Reticuli system, to establish a foothold on Earth at a place called Dulce Base, a secret underground complex near the Archuleta Mesa in New Mexico.

This came about after President Eisenhower signed a treaty with them at Holleman Air Force Base in 1953, but following a surprise attack on the humans of the base in 1975, the treaty was deemed worthless and the U.S. government was in a bind.

Fast forward to 1979...