(Bloomberg) -- U.S. Defence Secretary Lloyd Austin will criticize China’s actions in the South China Sea on a tour of Southeast Asia this week, while also seeking to reassure senior military officials that Washington remains a reliable partner.

Austin was greeted by Singaporean Defense Minister Ng Eng Hen and reviewed soldiers in dress uniform on Tuesday morning. He is to deliver a speech later in the day about the value America places on its regional partners before traveling to meet his counterparts in Vietnam and the Philippines.

In a pre-trip briefing, Austin stressed that the Indo-Pacific was America’s “priority theater of operations” and that he will continue to make the case for “a more fair, open and inclusive regional order.”

The top U.S. defense official was also explicit about the messages he will deliver to allies on China’s activities in the region, remarks are likely to prompt a rebuke from Beijing.

“We don’t believe that any one country should be able to dictate the rules or worse yet, throw them over the transom and in this regard I’ll emphasize our commitment to freedom of the seas,” Austin told reporters before he left. “I’ll also make clear where we stand on some unhelpful and unfounded claims by China in the South China Sea.”

Austin’s trip, his second to the region, comes at a time of mounting U.S.-China tensions and as countries across Southeast Asia struggle with a surge in coronavirus cases. Diplomats from Washington and Beijing held contentious meetings in the Chinese port city of Tianjin on Monday, where America’s No. 2 diplomat Wendy Sherman and Foreign Minister Wang Yi both aired the grievances of their governments.

See: U.S., China Leave Room to Talk After Contentious Meetings

His visit coincides with the U.S. military drawdown in Afghanistan, a move that will switch some Washington’s focus to the Western Pacific from the Middle East. That strategic shift will be part of talks during U.S. Secretary of State Antony Blinken’s trip to Asia this week. The top American diplomat will travel to New Delhi to meet with Indian Prime Minister Narendra Modi on Wednesday before flying to Kuwait.

One of Austin’s most significant public engagements on the trip will be delivering an address titled “The Imperative of Partnership” at an International Institute for Strategic Studies event in Singapore. Austin said the speech will focus on how the U.S. is “strengthening one of our strategic assets in the region, which is our powerful network of allies and partners.”

He also said he will brief military officials on how the U.S. is updating and modernizing its defense capabilities, and can help partners do the same to counter what he described as “changing forms of aggression and coercion that we’re all seeing.”

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