China's delegation at the Shangri-La summit in Singapore is emphasizing Beijing's firm stance regarding the South China Sea.

It said the deployment of garrisons and weapons there, is within the scope of China's sovereignty. Earlier, US defense secretary James Mattis harshly criticized China's actions. CGTN's Miro Lu has more.

Just hours after the US President Donald Trump announced that the highly-anticipated meeting with the DPRK leader Kim Jong Un in Singapore is back on track, US Secretary of Defense James Mattis told a room of regional allies that withdrawing or reducing military presence in the Korean Peninsula is not an option for now.

JAMES MATTIS US SECRETARY OF DEFENSE "Any discussion about the number of the US troops in the ROK is subject to the invitation to have them there and the discussion between the US and ROK, separate from the issue with DPRK. That issue will not come up in the discussion with the DPRK. Those troops are there is a reflection of the security issues there."

MIRO LU SINGAPORE "The U.S. military presence in the region is not limited to the Korean Peninsula. Farther down in the hotly disputed islands in the South China Sea, the U.S. issued a stern statement criticizing what they deem as the militarization of the region."

JAMES MATTIS US SECRETARY OF DEFENSE "China's militarization of artificial features in the SCS includes the deployment of anti-ship missiles, surface-to-air missiles, electronic jammers &, more recently, the landing of bomber aircraft at woody island despite China's claims to the contrary, the placement of these weapon systems is tied directly to military use for the purposes of intimidation and coercion."

Responding to Mattis' hardline talks, the Chinese delegates lashed out at the "irresponsible comments".

HE LEI, VICE PRESIDENT CHINESE ACADEMY OF MILITARY SCIENCES "The garrison and deployment of weapons in the reefs and islands in the South China Sea is within the scope of China's sovereignty. It is allowed by international law. Irresponsible talks by any other country are interference in China's internal affairs."

Observers say the South China Sea had not been a strategic rivalry issue until the United States decided to take that as a tool to spearhead China.

LANXIN XIANG PROFESSOR OF INTERNATIONAL HISTORY AND POLITICS GRADUATE INSTITUTE OF INTERNATIONAL AND DEVELOPMENT STUDIES, GENEVA "I think what Mattis' mistake is express this American attitude when United States is the only country sitting in a continent surround by two major oceans, which means their geopolitical situation is completely safe without fighting a war. Then sitting on that position to berate other players in the world, other regional players in the world for thinking geopolitically, even thinking the sphere of influence. That is a very hypocritical attitude."

MIRO LU SINGAPORE "Chinese foreign spokesperson responded to the US accusation as saying the US is like a robber playing a cop. The US military presence in the South China Sea is greater than that of China and other countries that surround the seas combined. Miro Lu, CGTN, Singapore."