BANGKOK - US Defense Secretary Mark Esper rebuked China's behavior in the South China Sea in a meeting Sunday with his Southeast Asian counterparts.
Esper, speaking at the ASEAN-US ministerial meeting of the annual ASEAN Defense Ministers' Meeting-Plus, also cast doubts on Beijing's sincerity in forging a "meaningful" Code of Conduct with the 10-member Association of Southeast Asian Nations.
"China's activities there are a threat not only to other claimants and to many Southeast Asian nations, but to all trading nations who value freedom of the seas, and the peaceful settlement of disputes," Esper said at the meeting.
"(China's) maritime claims in the South China Sea, exemplified by the illegitimate nine-dash line, are both unlawful and unreasonable, and counter to the July 2016 ruling of the UNCLOS Permanent Court of Arbitration at The Hague," he said.
The nine-dash line refers to a demarcation used by China for its claim in the South China Sea, where ASEAN members Brunei, Malaysia, the Philippines, and Vietnam also have claims. UNCLOS stands for the United Nations Convention on the Law of the Sea.
In a bid to clarify its maritime entitlements in the South China Sea amid China's aggressive assertion of its claims over almost the entire body of water, the Philippines sought arbitration in 2013 with the international tribunal and eventually won the case in 2016.
Rejecting the arbitration process and the ruling, China reclaimed disputed features in the South China Sea and fortified them with military installations, and has been driving away foreign fishermen, coast guards and militaries.
Esper said China has "stepped up its use of what it calls 'maritime militia vessels'" to ward off Filipino, Indonesian, Malaysian and Vietnamese sailors, and fishermen, as well as employing its coast guard to prevent Vietnam from "drilling oil and natural gas off its own shores."
"Through repeated provocative actions to assert the nine-dash line, Beijing is inhibiting ASEAN members from accessing over $2.5 trillion in recoverable energy reserves, while contributing to instability and increasing the risk of conflict," Esper said.
"This behavior contrasts sharply with the rules-based order we have all worked together to build for more than 70 years," he added.
Esper said Beijing's "actions in the South China Sea present a maritime challenge that requires a multilateral solution."
"I encourage you to use your sovereign spaces, as well as international ones, or risk losing them," he told his ASEAN counterparts, stressing, "multilateral approaches are key" and reaffirming Washington's intention to continue flying, sailing and operating "where international law allows."
"Together, we must stand for lawful uses of air and maritime spaces to push back against coercion and intimidation," he said.
Expressing skepticism over Beijing's "sincerity to negotiate a meaningful Code of Conduct that reinforces international law," Esper urged ASEAN not to allow the proposed set of guidelines "to be manipulated by the PRC to legitimize its egregious behavior and unlawful maritime claims, or to evade the commitments" it has signed up to.
He warned that "if this were to happen, the Code of Conduct would be counterproductive and harmful to all who value the freedoms enshrined in the UN Convention on the Law of the Sea." The United States is not a signatory to the 1982 accord.
ASEAN and China last year agreed on the text, which will form the basis of future COC negotiations. Aimed at managing tensions in the South China Sea, the envisioned Code of Conduct is hoped to be fully negotiated by 2021.
China has initially proposed in the COC that nonparty militaries who wish to hold exercises with ASEAN and China must have their approval, in an apparent swipe at the United States.
Esper underscored his country's freedom of navigation operations in the South China Sea, which he said has been most frequent this year compared to any in the past 25 years, as "particularly important in responding to steps Beijing has taken to militarize outposts" there.
"America's sustained military presence in the region is an enduring source of stability," he said, eliciting approval from Singaporean Defense Minister Ng Eng Hen, who spoke on behalf of all ASEAN ministers.
"I encourage all of us to work together to push back on this unacceptable behavior, to ensure we do not cede space or abdicate our rights," Esper said.
"For our part, the United States raises its concerns about Chinese behavior directly with the Chinese government. And we hope our words and actions provide you space to do the same."
The rivalry of the United States and China, the world's current leading powers, has extended to the influence they have over ASEAN, with each country holding a maritime exercise once with the bloc over the last two years.
At the ASEAN-China defense ministerial meeting earlier in the day, the South China Sea issue was also raised.
The two sides agreed in principle to conduct a second joint maritime exercise following their inaugural drills in 2018, Malaysian Defense Minister Mohamad Sabu told reporters afterward.
Mohamad said ASEAN again requested that the COC be respected and that Chinese Defense Minister Gen. Wei Fenghe responded that China is willing to work with ASEAN in addressing the sea dispute.
The two-day ADMM-Plus opened Sunday in Bangkok, as Thailand is this year's chair of ASEAN, which also includes Cambodia, Indonesia, Laos, Myanmar, and Singapore.
At an informal retreat of the ASEAN defense ministers following their meeting with Wei, some voiced concerns over the South China Sea row, but overall there was optimism about the progress of the COC negotiations.
The ADMM-Plus meeting also involves the defense chiefs from the ASEAN's eight regional partners -- Australia, China, India, Japan, New Zealand, South Korea, Russia, and the United States.
(Chananthorn Kamjan contributed reporting.)