US Acting Defense Secretary Patrick Shanahan on Saturday denounced China’s efforts to steal technology from other nations and militarise man-made outposts in the South China Sea as a “toolkit of coercion,” saying activities by Beijing the US perceives as hostile must end.

In his first major speech on the international stage, Shanahan mixed sharp criticism of China and warnings of North Korea’s “extraordinary” threat with vows that the US will remain strongly committed to the Indo-Pacific region and is ready to invest billions of dollars in securing its stability.

While he didn’t specifically name China in early parts of his speech, he made clear who his target was, making pointed references to Beijing’s campaign to put advanced weapons systems on disputed islands in the region.

“If these trends in these behaviours continue, artificial features in the global commons could become tollbooths. Sovereignty could become the purview of the powerful,” he said. His remarks underscore America’s frayed relations with China, as the Trump administration wages a trade war with Beijing, imposes sanctions on Chinese tech giant Huawei and approves a weapons sale to Taiwan, the self-ruled island the Communist mainland claims as its own territory.

And they reflect America’s new national defense strategy that declared great power competition with China and Russia as top priorities.

Shanahan’s speech is also arguably an audition to both the world and US top leaders in Congress, as his nomination for permanent secretary has still not been sent to Capitol Hill by President Donald Trump.

And listening closely in the audience were nervous allies and partners in the region who are worried about the economic impact of the US-China trade dispute and the political blowback of America’s complaints about Beijing’s rapid progress in hypersonic weapons, nuclear technology and space launches.