US military challenged fewer maritime claims with FONOPs in FY 2020 March 10 The U.S. warship John S. McCain conducted a freedom of navigation operation, or FONOP, near the contested Spratly Islands in the South China Sea on Dec. 22, 2020. (Navy) The U.S. military used freedom of navigation operations, or FONOPs, to challenge 28 excessive maritime claims by 19 nations worldwide in fiscal 2020, the Pentagon said Wednesday. That marks a reduction from fiscal 2019, when U.S. forces challenged 36 maritime claims by 22 countries, according to Defense Department data. The Pentagon does not make public precisely how many FONOPs are undertaken in a given year, though most are conducted by U.S. Navy ships to challenge claims on waters that are international by law.