In September, President Joe Biden and the prime ministers of Australia and the U.K. announced a new defense partnership, surprising allies and competitors alike.

The initiative, known as AUKUS, infuriated France, which lost out on the sale of submarines worth close to $60 billion, and alarmed China, which sees the pact as a direct threat.

Although AUKUS leaders say their initiative isn’t aimed at any country, in particular, it is clear that the deal was designed to counter Chinese influence and ambitions in the Indo-Pacific region.

The pact centers on an agreement for the U.S. and U.K. to provide nuclear-propulsion technology to Australia, but that is only the tip of a collaboration iceberg between the three countries. Their cooperation goes back decades, and special operations forces have been a key component.

Cut From the Same Cloth

Most modern Western special-operations units can trace their lineage to the British Special Air Service in World War II. The commonalities that were created became clear during the past two decades of war in the Middle East and Africa.

Allied countries often train together to ensure interoperability, to learn from one another, and to hone their war-fighting skills in a more realistic environment. The U.S. Army’s Delta Force has a deep relationship with the Australian SAS, and the two units often train in Australia and the United States.

In addition to regular training, the special operations communities of the three countries share a close relationship through exchange programs in which individuals or groups from one unit spend time serving with one of their direct counterparts. These exchange programs have existed for decades.

Most exchanges take place at the Tier 1 level, among the U.S.’s Delta Force and Naval Special Warfare Development Group (formerly known as SEAL Team Six), the Australian Special Air Service Regiment (SASR), and the British Special Air Service (SAS) and Special Boat Service (SBS).

Insider understands that other Tier 1 units from the U.S. and U.K. also exchange operators, though the exact units and their activities have not been publicly disclosed.

Exchanging Troops

Australian commandos have spent time in the U.S. in exchange programs with Delta Force and Naval Special Warfare Development Group. Likewise, American special operators have been seconded to the Australian SAS. That relationship started during the Vietnam War when Australian SAS troopers joined Navy SEAL platoons in the Mekong Delta and targeted Vietcong insurgents.

U.S. special operations units also share a very close relationship with their British counterparts. Delta Force, the U.S. Army’s premier special missions unit for counterterrorism and hostage-rescue, was created after its founder, Col. Charlie Beckwith, then a young Green Beret, spent two years as an exchange officer with the SAS.

The links between Australia and the U.K. are even tighter. Australia’s primary special operations unit, the Special Air Service Regiment (SASR), is modeled on and named after the British Special Air Service (SAS). Exchanges between the two communities are common.

During the infamous Bravo Two Zero mission in the first Gulf War, two of the eight troopers deployed with the British SAS unit involved weren’t British. One was a former Australian special forces Commando, and the other a New Zealander on exchange from the New Zealand Special Air Service.

Usually, such exchange programs remain in the shadows because of the sensitive and classified work that these units do. When someone passes the selection to join Delta Force or the Naval Special Development Group, their identity is classified and they are placed on a special Department of Defense roster.

Sometimes their actions on the ground merit recognition, and their names or unit affiliations are revealed. The same goes for the exchange programs. In the opening days of the war in Afghanistan, an exchange program between the Naval Special Warfare Development Group and the British SBS received some unexpected attention.

In the weeks after the September 11 attacks, American and coalition special operations forces joined anti-Taliban fighters to topple the Taliban and Al Qaeda. While Delta Force was looking for Osama bin Laden in the Tora Bora mountains, hundreds of Taliban prisoners held in a fortress in Mazar-e-Sharif revolted, killing CIA officer Mike Spann, the first American to die in Afghanistan. Green Berets, CIA officers, and an SBS team joined anti-Taliban fighters and swiftly quelled the revolt.

The actions of one SBS member revealed the extent of these exchange programs. Chief Petty Officer Stephen Bass received the Navy Cross, the U.S.’s second-highest award for valor, and the British Military Cross. Although the Navy Cross citation said Bass’ parent unit was SEAL Team 1, he was in fact a SEAL Team 6 operator on a two-year exchange program with the British.

AUKUS Special Operations

While the AUKUS pact focuses on defense technology, it’s also an opportunity for the three countries’ special operations communities to work together even more closely to counter Chinese influence and aggression in the Indo-Pacific.

In the era of great-power competition — which can range from intense geopolitical competition to proxy wars or even open conflict — access to contested spaces is key.

To counter Chinese activity, U.S. forces need to be able to reach where it’s happening, whether in the buffer zone Beijing has created with its man-made islands in the South China Sea or even the Chinese mainland.

Australia has the regional knowledge and infrastructure to support such operations, and the AUKUS initiative is another way to take advantage of it.

This article was written by Stavros Atlamazoglou and originally published on the Insider.