The alliance has grown into a robust global surveillance mechanism, adapting to new domains such as international terrorism, cyberattacks, and contemporary regional conflicts.

The alliance's activities, often shrouded in secrecy, have occasionally come under scrutiny for their implications on privacy and civil liberties, sparking debates and legal challenges.

Five Eyes remains a key element in the intelligence and security landscape of each member country, providing them a strategic advantage in understanding and responding to global events.

[14] The first record of these meetings is a February 1941 diary entry from Alastair Denniston, head of Bletchley Park, reading "The Ys are coming!"

[15] The formal Five Eyes alliance can be traced back to the August 1941 Atlantic Charter, which laid out Allied goals for the post-war world.

On 5 March 1946, the two governments formalized their secret treaty as the UKUSA Agreement, the basis for all signal intelligence cooperation between the NSA and GCHQ up to the present.

[18] Over the course of several decades, the ECHELON surveillance network was developed to monitor the military and diplomatic communications of the Soviet Union and its Eastern Bloc allies.

[24][25] In 1961, SIS and the CIA jointly orchestrated the assassination of the Congolese independence leader Patrice Lumumba, an operation authorized by out-going US President Dwight D. Eisenhower the year before in 1960.

[35] By the end of the 20th century, the FVEY members had developed the ECHELON surveillance network into a global system capable of collecting massive amounts of private and commercial communications including telephone calls, fax, email, and other data traffic.

[39] The program was first disclosed to the public in 1972 when a former NSA communications analyst reported to Ramparts magazine that the Agency had developed technology that "could crack all Soviet codes".

[40] In a 1988 piece in the New Statesman called "Somebody's listening", Duncan Campbell revealed the existence of ECHELON, an extension of the UKUSA Agreement on global signals intelligence.

"[19] In the aftermath of the September 11 attacks on the World Trade Center and the Pentagon, Five Eyes members greatly increased their surveillance capabilities as part of the global war on terror.

[59] In 2013, documents leaked by the former NSA contractor Edward Snowden revealed the existence of numerous surveillance programs jointly operated by the Five Eyes.

The following list includes several notable examples reported in the media: In March 2014, the International Court of Justice (ICJ) ordered Australia to stop spying on East Timor.

[67] On 1 December 2018, Canadian authorities arrested Meng Wanzhou, a Huawei executive, at Vancouver International Airport to face charges of fraud and conspiracy in the United States.

"[71] Starting in 2019, Australian parliamentarians as well as US Secretary of State Mike Pompeo prompted the United Kingdom not to use Huawei technology in its 5G network.

[81] During an interview with The Economist, Prime Minister Christopher Luxon said that he was looking to "diversify New Zealand's diplomatic and trade relationships away from its reliance on China".

[82] In late April 2021, the Global Times reported that China's Ministry of State Security will monitor employees of companies and organisations considered to be at risk of foreign infiltration while they travel to the Five Eyes countries.

[83][84] In mid-December 2021, the United States Secretary of State, the Foreign Ministers of Australia, Canada, and New Zealand, and the UK Foreign Secretary issued a joint statement criticising the exclusion of opposition candidates by Hong Kong national security law and urging China to respect human rights and freedoms in Hong Kong in accordance with the Sino-British Joint Declaration.

"[92] However, in recent years, FVEY documents have shown that member agencies are intentionally spying on one another's private citizens and sharing the collected information with each other.

[11][93] Shami Chakrabarti, director of the advocacy group Liberty, claimed that the FVEY alliance increases the ability of member states to "subcontract their dirty work" to each other.

[109] [110] According to French news magazine L'Obs, in 2009, the United States propositioned France to join the treaty and form a subsequent "Six Eyes" alliance.

[112][113] At the time, several members of the United States Congress, including Tim Ryan and Charles Dent, were pushing for Germany's entry to the Five Eyes alliance.