Simplify the following text for a Grade 10 native English-speaking person.
Original: The M1 remains the principal main battle tank of the United States Army and Marine Corps , and the armies of Egypt , Kuwait , Saudi Arabia , Australia , and in 2010 Iraq .
Simplified: It is the principal main battle tank of the United States Army and Marine Corps , and the armies of Egypt , Kuwait , Saudi Arabia , Australia , and in 2010 Iraq .