The Philippine government said Monday that like Vietnam, it opposes China’s recent test of a newly completed runway on one of seven islands Beijing has constructed in the disputed South China Sea. Department of Foreign Affairs spokesman Charles Jose said the government was considering protesting China’s action, as Vietnam did, adding that the test at Fiery Cross Reef “adds to tension and uncertainties in the region.”

Vietnam last week protested the test, saying it violated Hanoi’s sovereignty, and demanded that China stop such actions. China rejected Hanoi’s protest and will likely dismiss Manila’s concerns as well. Chinese Foreign Ministry spokeswoman Hua Chunying said Saturday that China deployed a “civil aircraft” on the island, which it calls Yongshu Jiao, to determine whether the new airfield in what she said was Chinese territory conformed to civil aviation standards.

The early diplomatic tussle presages a continuation this year of tense exchanges, mainly among China, Vietnam and the Philippines, over long-disputed and potentially oil- or gas-rich offshore territories also claimed by Taiwan, Malaysia and Brunei.