BEIJING, Jan. 20 (Xinhua) -- A Chinese Foreign Ministry spokesperson Saturday vowed "necessary measures" will be undertaken to safeguard the country's sovereignty after a U.S. warship entered waters surrounding Huangyan Island in the South China Sea.

When responding to a relevant question from the press, spokesperson Lu Kang confirmed that the USS Hopper, a guided missile destroyer, sailed within 12 nautical miles of the Chinese island on Wednesday evening without Chinese government permission.

According to Lu, the Chinese Navy has conducted an identification and warning process to drive the U.S. warship away.

Lu said the U.S. warship has impaired China's sovereignty and security interests, and caused a serious threat to Chinese vessels and personnel working in the area.

The spokesperson said the U.S. side's behavior has broken basic protocols of international relations, voicing China's strong dissatisfaction.

"China will take necessary measures to firmly safeguard its sovereignty," he said.

Lu reiterated that China has indisputable sovereignty over Huangyan Island and its adjacent waters.

"China respects and safeguards the freedom of navigation and overflight in the South China Sea for all countries in accordance with international law, but resolutely opposes any country's move to impair China's sovereignty and security interests in the name of freedom of navigation and overflight," Lu said.

"We strongly urge the U.S. to rectify its mistake immediately and cease this kind of provocation so as not to harm Sino-U.S. relations and regional peace and stability," he said.