SYDNEY – China has stepped up its surveillance of strategic sea routes in the western Pacific only weeks after Australia announced a major upgrade of its northern air defenses that will help the United States to project more force into the region, including in the South China Sea.

Australia’s Defense Department confirmed it had been tracking a Chinese oceanographic ship for the past two months as it conducted deepwater surveys on a course from eastern China to the coast of Western Australia.

The route, which took the vessel through the Java Sea in the Indonesian archipelago to waters near the Australian territory of Christmas Island, is used regularly by Australian submarines transiting to the South China Sea.

“Beijing is keen to know as much as it can about … these submarine routes, and it would also be wanting to test and monitor the Australian response to the presence of a high-tech Chinese vessel that’s loitering off its coast,” a defense official told the Australian Broadcasting Commission.

Identified as the Xiang Yang Hong 01, the ship anchored in international waters off Naval Communication Station Harold E Holt, a secretive base on the North West Cape that sends very low frequency radio transmissions to Australian and American ships and submarines in the Indo-Pacific.

Australia’s Space Surveillance Telescope at the Naval Communication Station Harold E Holt. Photo: Twitter

Formerly run by US defense agencies, it also houses a Space Surveillance Telescope, part of the US global Space Surveillance Network, that can track space traffic and debris. It is said to be operated remotely from an air force base.

USS Texas, an American fast attack submarine, was on a routine visit to the Stirling naval base near Perth during the Chinese ship’s activities.

The Xiang Yang Hong 01 was detected in the territorial waters of Palau in 2018, one of three Chinese ships that were then operating in the region. It withdrew when Palau’s government lodged an official protest in Beijing.

Two other Chinese ships appeared off Papua New Guinea’s naval facility at Manus Island, which Australia and the US are upgrading and will jointly operate as a forward base for the South China Sea and Western Pacific.

Australia also confirmed late last month that it will spend A$1.1 billion (US$717 million) to upgrade the Tindal airbase in its Northern Territory so it can handle larger planes, including refueling aircraft and long-range US bombers. Some Australian F-35 joint strike fighters will be based at Tindal, reports said.

Fighter jets in a row at Australia’s Tindal Air Base. Photo: Australia Defense Department

Naval assets are undergoing similar improvements, with plans to spend A$715 million (US$466 million) at Coonawarra naval base and support facilities near Darwin so the US Navy can dock more warships. Due to be opened in 2023, it will include a wharf that can handle helicopter carriers.

The US is reportedly spending US$8 billion itself over the next decade to beef up Northern Territory facilities to be used by a rotating detachment of marines for training and weapons testing.

Australian officials have hinted that the detachment, now at its full strength of 2,500, could be increased.

Pentagon analysts fear that China is building a sphere of influence in the Western Pacific to support its so-called Third Island Chain, a line pivoting south from the Aleutian Islands to Tonga and New Zealand.

Beijing’s First Island Chain covers the South China Sea and nearby East China Sea, as well as Taiwan, Japan and much of Southeast Asia, and is designed to secure sea routes for the delivery of its Middle East oil supplies.

The Second Island Chain extends from Japan’s Ogasawara Islands and the Mariana Islands to Micronesia, Palau and West Papua, which is controlled by Indonesia. This chain includes an important US military base at Guam.

Analysts believe China has sights on securing fourth and fifth island chains, leveraging into a new base Beijing established in Djibouti and port facilities in has helped to build in South Asia.

Map: Asia Maritime Transparency Initiative/Center for Strategic and International Studies

A Pentagon map appears to confirm the heightened Chinese naval activity. Included in the FY2021 Defense Budget Overview, the map shows a dense concentration of activity in a zone that ranges from the South China Sea passageway to Indonesia, Papua New Guinea and northwestern Australia.

One issue raised in the Pentagon report was China’s potential control of undersea telecommunication cables that run on a west-east axis through the region. Chinese control of the cables could paralyze some regional economies in the event of a conflict.

“Almost the entire internet and trillions of dollars in trade are carried today on a largely unsecured network of undersea cables,” the report noted.

Admiral Philip Davidson, commander of the US Indo-Pacific Command, said during a visit to Australia last month: “The Communist Party of China seeks to control the flow of trade, finance, communications, politics and the way of life in the Indo-Pacific.”

Beijing insists that its intentions are entirely peaceful. Foreign Ministry spokesman Lu Kang said last year that China’s “scientific research” in the Western Pacific was “totally in line with the United Nations Convention on the Law of the Sea and made contributions to maritime scientific study.”