1965 – Britain detaches the Chagos Archipelago from Mauritius, evicts up to 2,000 residents and establishes the U.S. Naval Support Facility Diego Garcia, laying the foundation for the strategic base that later becomes central to UK‑US security cooperation [7].

1966 – The United Kingdom and the United States sign a bilateral treaty governing the British Indian Ocean Territory, obligating mutual use of Diego Garcia and cementing the long‑term military partnership [7].

2019 – The International Court of Justice issues an advisory opinion that the UK’s decolonisation of the Chagos Islands was illegal and orders the territory’s return to Mauritius, creating a legal backdrop for later negotiations [12].

May 2025 – The UK and Mauritius sign a treaty transferring sovereignty of the Chagos Islands to Mauritius while leasing Diego Garcia back to the United Kingdom (and thus the United States) for 99 years at an average £101 million per year, with a total net cost of £3.4 billion and a £40 million trust fund for displaced Chagossians [13][12][6].

June 2025 – U.S. B‑2 Spirit bombers conduct a 37‑hour raid on Iranian nuclear sites launched from Missouri, deliberately avoiding RAF Fairford and Diego Garcia, demonstrating the bases’ potential but not yet required role in long‑range strikes [5].

2025 (later) – Diego Garcia supports U.S. B‑2 operations in the Yemen Houthi campaign, underscoring its operational importance for regional power projection [7].

Jan 20 2026 – President Donald Trump posts on Truth Social that the Chagos handover is “great stupidity,” arguing it weakens U.S. security and linking the criticism to his broader “Greenland” push; the UK government counters that the United States still backs the deal and that national security is not compromised [4][10][11][12].

Jan 21 2026 – Prime Minister Keir Starmer tells the Commons that Trump’s “great stupidity” remarks differ from his earlier support and accuses the president of using the issue to pressure Britain over Greenland, while reiterating that the lease “will not be compromised” [9].

Jan 26 2026 – The UK Foreign Office reaffirms its commitment to the Chagos handover despite U.S. criticism; Minister Stephen Doughty blames a “wrecking amendment” in the House of Lords for delaying the bill, and peers postpone debate citing “changing geopolitical circumstances,” while opposition MPs demand clarification of the 1966 treaty before ratification [3].

Feb 1 2026 – Maldives President Mohamed Muizzu proposes that the Maldives assume Chagos sovereignty while preserving the U.S. base, citing historic ties; Trump again denounces the UK‑Mauritius handover as “an act of GREAT STUPIDITY” and suggests acquiring Greenland instead [8].

Feb 5 2026 – Trump warns on Truth Social that the United States will “militarily secure Diego Garcia if the lease is threatened,” citing recent B‑2 deployments from the island in the Yemen Houthi campaign and asserting his right to reinforce the base [7].

Feb 18 2026 – Trump publicly urges “Do not give away Diego Garcia,” labeling the transfer a “blight on our Great Ally”; the U.S. State Department confirms support for the UK‑Mauritius agreement, the UK Foreign Office calls the lease “crucial to security,” and four Chagossians stage a protest on the atoll against the handover [2].

Feb 19 2026 – The United Kingdom announces it has not authorised U.S. use of RAF Fairford or Diego Garcia for any potential Iran strike, citing a breach of international law; Trump posts that the world will know “over the next, probably, 10 days” whether the U.S. reaches a nuclear deal with Iran or proceeds with military action, and Liberal Democrat leader Sir Ed Davey accuses Trump of “bullying” over base use [1].

Feb 20 2026 – Prime Minister Starmer tells officials that allowing RAF Fairford or Diego Garcia for an Iran attack “would be a breach of international law,” while Trump, after a phone call with Starmer, again calls the lease a “big mistake” and urges U.S. use of the bases; the U.S. State Department reaffirms backing the UK‑Mauritius deal, and analysts warn that a prolonged Iran campaign would require forward bases like Diego Garcia for rapid re‑arm and missile‑threat avoidance [5].

Feb 21 2026 – The UK Parliament moves draft legislation toward ratifying the May 2025 treaty, confirming the 99‑year lease of Diego Garcia at £101 million per year, the £3.4 billion hand‑over cost, and the £40 million Chagossian resettlement trust; opposition MPs cite Mauritius’s growing ties with China as a security concern [13].

Feb 29 2026 (anticipated) – Trump’s promised ten‑day window for a decision on the Iran nuclear deal or military action is expected to close, potentially shaping whether the United States again seeks forward basing rights in the Indian Ocean [1].