The Torres Strait that separates the Australian mainland from the island of Papua to the north is an important component in Australia’s defence and security architecture, although it is one that is often overlooked beyond border protection terms.
Measuring 150 km (93 miles) at its narrowest point and is frequently used by commercial shipping heading up and down Australia’s east coast to and from the rest of the world.
Up to 30 large commercial ships, including oil tankers, transit through the Prince of Wales Channel linking the Arafura Sea with the Coral Sea on a busy day, making it the sole maritime chokepoint in Australian waters.
The strategic importance of the Torres Strait and its islands was recognised as far back as the 1940s when Horn Island (Ngurapai), 16 km (10 miles) north of the Australian mainland was chosen as the site of an advanced operational airfield.
The airfield was a key transit stop for Australian and Allied aircraft heading to the combat zone in Papua New Guinea, and eight separate Japanese air raids between March 1942 and June 1943 made the island the second most attacked location in Australia behind Darwin.
“Today, the airport remains a hub for air links to the Australian mainland and throughout the outlying islands,” explained Vanessa Seekee, who runs heritage tours of Horn Island and manages the Torres Strait Heritage Museum showcasing the region’s cultural and military history. “The airport sees up to 1,300 movements a month, mostly helicopters and small passenger transport aircraft.”
Defence also has a permanent presence on the islands, with C Company of the Army’s 51st Far North Queensland Regiment based at Sarpeye Barracks on Thursday Island. The 51 FNQR is an Australian Army Regional Force Surveillance Unit (RFSU) whose primary role is to conduct reconnaissance and surveillance tasks in support of border security operations.
It is one of several government agencies responsible for overseeing the Torres Strait Treaty, which defined the border between Australia and Papua New Guinea following the latter’s independence in 1975.
The treaty also saw the establishment of the Torres Strait Protected Zone, which allows indigenous Torres Strait Islanders and coastal Papua New Guinea people to maintain their traditional ways of life, and "allows traditional people to move freely within the Protected Zone (without passports or visas) for traditional purposes."
The unit is also responsible for observing and surveillance of foreign warships transiting the Strait, and took the images released by Defence of the Chinese People’s Liberation Army Navy (PLAN) task group that sailed through in April 2022 after having been accused to shining a high-powered laser at an Australian P-8A Poseidon maritime patrol aircraft in the Arafura Sea.
PLAN Type 815 intelligence gathering vessels have also used the channel for transits, and Dr Euan Graham, a Senior Analyst at the Australian Strategic Policy Institute, notes that with the strait being an international shipping channel, transit rights for foreign naval vessels through it are guaranteed.
He told ADM that he expects a PLAN presence in the strait going forward to be a regular occurrence as they through the Indonesian archipelago and Torres Strait en route to Solomons and other Southwest Pacific destinations.
“The Torres Strait is likely to become more important in future because PNG could be a key access point for Australia to project force to its north,” he said of the wider strategic context, as well as noting he foresees a possible wider role for the Army in the region in times of contingency.