Complex sentence: Philip Schneider, an ex-government structural engineer, reported building underground military bases around the United States, and claims he and two other people survived an incident in 1979 between Grey aliens and U.S. military forces at a location called Dulce Underground Base.
Split into simpler sentences: Philip Schneider, an ex-government structural engineer, reported building underground military bases around the United States. He also claimed he and two other people survived an incident in 1979 between Grey aliens and U.S. military forces at a location called Dulce Underground Base.