Foreign Affairs Secretary Teodoro Locsin Jr. said Wednesday that the West Philippine Sea "is ours" and that China, from whom President Rodrigo Duterte sought investments and loans, "took it."
Teodoro made the remark in reply to a Twitter follower who asked for his agency's stand on the "clear evidence of China's power" in the waterway.
"The stand is that it is ours. And they took it. World's highest court ruled that. Period," said the official.
"Now the question is how to take it back," he added.
China refuses to recognize a United Nations-backed arbitral tribunal's ruling that invalidated its sweeping 9-dash line claim over the South China Sea.
Philippine authorities have repeatedly raised concerns over China's activities in the disputed waters, particularly militarization efforts, which Beijing denied.
President Rodrigo Duterte has said in several occasions that the Philippines could not afford to go to war against its more powerful Asian neighbor.
Locsin, in his tweet, said he has "no fear of war."
"One attack on a public vessel triggers World War 3 with the USofA which is impervious to attack from Asia," he said.
Locsin also claimed that Manila could not defend its maritime territory before because former US President Barrack Obama "was in love with China" and told Beijing it was "okay to take what it wants from the Philippines."
Washington and Manila are bound by a half century-old Mutual Defense Treaty, its respective military forces engaging in regular war games that see thousands of US troops and American military hardware brought to Manila.
US is Philippines' 'only military ally': Locsin
However, the treaty's role in the Philippines' sea dispute with China is unclear.
Under US interpretation, the treaty covers only "metropolitan" Philippines and does not include the Filipino-occupied areas in the South China Sea, Defense Secretary Delfin Lorenzana said last year as he sought a review of the pact.
Does PH-US Mutual Defense Treaty cover the South China Sea?
Before he stepped down from office, Obama had urged Beijing to adhere to the rule of law, saying the landmark ruling against its claims to South China Sea is "binding."