Simplify the following text for a Grade 7 native English-speaking person.
Original: Other sites of interest are the remains of American aircraft that crashed on Funafuti during World War II , when the airstrip was used by the American forces to defend the Gilbert Islands ( now Kiribati ) .
Simplified: Other sites of interest are the remains of United States aircraft that crashed on Funafuti during World War II , when the airstrip was used by the U.S. forces to defend the Gilbert Islands and the Marshall Islands .