The US military carried out freedom of navigation operations challenging the maritime claims of China, Iran and 10 other nations last year, asserting its right to use the seas in defiance of their restrictions, a Pentagon report says.
The Defense Department's annual Freedom of Navigation Report to Congress for the 2013 fiscal year on Thursday (local time) showed the US military targeted not only countries such as Iran, with whom it has no formal relations, but treaty allies like the Philippines, too.
The US military conducted multiple operations targeting China over what Washington believes are "excessive" claims about its maritime boundaries and its effort to force foreign warships to obtain permission before peacefully transiting its territorial seas.
US operations challenged Iran for trying to restrict the use of the Strait of Hormuz to ships from countries that have signed the UN Convention on the Law of the Sea, an accord the United States has not formally adopted but treats as generally accepted customary law.
The report covers activity in the 2013 fiscal year that ended September 30, before the latest tensions over an incident between US and Chinese warships in the South China Sea and Beijing's declaration of an air defence identification zone over the East China Sea, which Washington rejected.
The United States carries out freedom of navigation operations by sending navy ships into disputed areas in an effort to show that the international community has not accepted claims made by one or more countries.
The operations, which began in 1979, are co-ordinated by the State and Defense departments and are meant to be consistent with the UN Law of the Sea Convention, even though Washington has not formally adopted the agreement.
A US defence official, speaking on condition of anonymity, said the country whose laws are being challenged often are not even aware a US ship has been there, which is one reason for issuing an annual report after the fact to note the complaint.
"There are times that coastal states detect us executing the operation and we respond (with a) bridge-to-bridge query and they tend to be professional," the official said.
Incidents like the 1988 bumping of two US ships by Soviet vessels during a freedom of navigation operation in the Black Sea are uncommon, he said. That incident led the two countries to reach a bilateral understanding on the rights warships have in transiting the territorial seas of other states.
In addition to China, Iran and the Philippines, US operations in 2013 challenged claims by Cambodia, India, Indonesia, Libya, Malaysia, Maldives, Oman, Taiwan and Vietnam. All countries but Cambodia were targeted more than once.
Since 1991, the United States has conducted more than 300 freedom of navigation operations challenging maritime claims by 53 different countries worldwide, from Albania, Ecuador and Denmark to Pakistan and Yemen.
Iran and the Philippines have been challenged most frequently. Iran has appeared on 19 of the 21 lists submitted to Congress since 1991, while the Philippines has appeared on 18. Cambodia, the Maldives, India and Oman also frequently appear.
China has been on the list 11 times, the same as Indonesia and one less than Burma.
The most frequent US complaint is with countries that measure the start of their territorial waters by drawing a straight line between two points on the coast or along offshore islands, thereby enclosing a vast expanse of sea.
Washington disagrees with the Philippines' designation of the seas bounded by the island chain as internal waters and therefore off limits to foreign ships or overflight by foreign aircraft.