The guided-missile destroyer USS Wayne E. Meyer passed near the Parcacel Islands which are claimed by China, Taiwan and Vietnam. They are referred to as Xisha in Chinese and Hoang Sa in Vietnamese. In a statement 7th fleet Commander Reann Mommsen said the move “challenged the restrictions on innocent passage imposed by China, Taiwan, and Vietnam, and also contested China's claim to straight baselines enclosing the Paracel Islands”.
He added: “China, Taiwan, and Vietnam each claim sovereignty over the Paracel Islands. All three claimants require either permission or advance notification before a foreign military vessel engages in 'innocent passage' through territorial seas.
“The unilateral imposition of any authorisation or notification requirement for innocent passage is not permitted by international law, so the United States challenged these requirements.”
The move sparked a fiery response from the Chinese Defence Ministry.
In a statement it commented: “The US side has been practicing 'navigational hegemony' in the South China Sea for a long time.
“Such actions have seriously undermined China's sovereign interests, and proven the US side's complete lack of sincerity in maintaining global peace as well as regional security and stability.”
China has the largest territorial claim in the waters, which one-third of international shipping passes through.
The US Navy is believed to have undertaken three freedom of navigation exercises this year.
Taiwan’s claims overlaps those of China.
Both Taipei and Beijing claim to be the legal government of China.
After the Chinese Communist Party (CCP) won the Chinese Civil War, they founded the People’s Republic of China (PRC).
The defeated Kuomintang (KMT) fled to Taiwan which become the new Republic of China (ROC).
The Pan-Blue coalition is a camp within Taiwanese politics that favours Chinese unification or closer economic linkage to the PRC.
The Pan-Green coalition is a loose camp of parties which favour Taiwanese independence.
Taiwanese President Tsai Ing-wen’s Democratic Progressive Party is in the Pan-Green camp.
Mrs Tsai has previously said a declaration of independence, which would like infuriate Beijing, is not necessary due to Taipei’s de facto independence.
The ROC took China’s seat at the United Nations until 1971.
Whilst several countries have unofficial relations with Taipei, only 17 UN member or observer states give it formal recognition.
None of these are based in Asia.
Beijing has also been locked in a disputes with The Philippines in the South China Sea.
Manila’s claims overlap over Scarborough Shoal and the Spratly Islands.
A 2016 ruling from The Hague dismissed China’s claims of rights to resources with the nine-dash line as having no legal basis.