Updated

U.S. Defense Secretary James Mattis says returning three war-trophy church bells to the Philippines will help cement ties between the two countries.

Mattis was at F.E. Warren Air Force Base in Cheyenne on Wednesday to formally begin the repatriation of the Bells of Balangiga over the next several weeks.

U.S. Army soldiers took the bells after an attack killed 48 American troops in 1901, during the U.S. occupation of the Philippines. Two of the Bells of Balangiga are at the base, and the third is with the U.S. Army in South Korea.

Some veterans and officials in the U.S. oppose returning the bells, calling them memorials to American war dead.

Filipinos revere the bells as symbols of national pride. Philippine President Rodrigo Duterte has repeatedly called for their return.