Updated

The Philippine president has told the military to assert the country's ownership of a vast ocean region off its northeastern coast where Chinese survey ships were seen operating last year.

President Rodrigo Duterte said Monday he ordered the military to assert Philippine ownership of Benhan Rise to China in a friendly way, repeating that his country has no option but to be diplomatic because "I cannot match the might of China."

Philippine Defense Secretary Delfin Lorenzana said last week that the military had monitored Chinese survey ships crisscrossing the offshore region suspiciously from July to December last year, adding that the U.N. Commission on the Limits of the Continental Shelf declared in 2012 that the undersea area was part of the Philippine continental shelf.