(CNN) China's Defense Minister told his US counterpart that Washington must stop "flexing its muscles" in the South China Sea when the two met Monday, according to a spokesman for Beijing.

At the same time, China announced that its new domestically produced aircraft carrier was headed to the South China Sea for training and research purposes.

US Defense Secretary Mark Esper and Chinese Defense Minister Wei Fenghe met Monday in Bangkok, where the two were attending a meeting of defense officials from the Association of Southeast Asian Nations (ASEAN) and other countries.

Wei and Esper discussed a host of issues -- including the political unrest in Hong Kong and the status of the South China Sea, Chinese Defense Ministry spokesman Wu Qian said.

Much of the international community views China's maritime claims in the region as excessive and a violation of international law. The US also accuses China of militarizing islands in the sea, and regularly sails warships in the region as part of operations to challenge Beijing's claims and ensure "freedom of navigation."

Read More