The American people regularly list the United Kingdom as our closest ally, and for good reason. We don’t just talk about being allies; we actively work together to protect each other’s interests.

That’s why the United Kingdom’s possible transfer of the Chagos Archipelago, including the joint US-UK military base on the island of Diego Garcia, to Mauritius is so deeply concerning. Any deal that jeopardises the security of Diego Garcia would not only threaten our shared military installation, but it would also undermine the very idea that the United Kingdom is the type of friend Americans can trust to have our backs, and vice versa.

Since the 1970s, Diego Garcia has been the crown jewel of the United Kingdom’s military assets. Together, American and British forces have used Diego Garcia to conduct training missions, reload submarines, and respond to tensions throughout the Middle East, Africa, and Asia. Most recently, the United States has relocated several B-2 bombers to Diego Garcia to help deter Iran’s aggression toward demonstrators.

Perhaps the only person who truly understands just how valuable Diego Garcia is to the shared security interests of American and British forces in the Indo-Pacific is Chinese president Xi Jinping. Chinese forces have been trying to infiltrate our military installations on Diego Garcia for years, and it’s no coincidence that China has been aggressively pursuing a relationship with the Mauritian government during that same timeframe.

President Xi’s charm offensive in Mauritius is fuelled by two significant deals that position the island nation as the final stepping stone to Diego Garcia. Mauritius is a signatory to the Chinese-backed Pelindaba Treaty, otherwise known as the African Nuclear-Weapon-Free Zone treaty, which prohibits the research, stockpiling, and possession of nuclear weapons across the African continent.

Mauritius is also a partner to the Forum on China-Africa Cooperation trade and security agreement between China and 53 African nations. The Forum’s 2024 Beijing Action Plan reinvigorated its commitment to building nuclear-weapon-free zones. As a result of these agreements, Mauritius, at minimum, will be under intense pressure – and likely a binding legal obligation – to provide China with the opportunity to force inspections of the military equipment on Diego Garcia.

President Xi has been so eager to see Mauritius take possession of the Chagos Archipelago that he has already been caught floating Chinese spy balloons in the airspace above Diego Garcia in hopes of catching a closer glimpse of the operations underway by American and British troops on the island. The Royal Navy has managed to fend off similar espionage missions by Chinese spy boats along the coast of Diego Garcia, but the effort to deter Chinese intelligence operations would become nearly impossible with Mauritius in control of the surrounding islands.

The United Kingdom cannot cede the Chagos Archipelago to Mauritius without handing the keys of Diego Garcia to the Chinese Communist Party.

Even under the best circumstances, the hypothetical 99-year lease of Diego Garcia from Mauritius would drain British taxpayers of millions of pounds per year for a military base so swarmed by Chinese spies that it renders the island’s strategic value worthless. Under the worst-case scenario, British taxpayers realise they’re paying billions of pounds for a base we cannot secure and elect a government that will hand over Diego Garcia to Mauritius entirely. Mauritius is our friend, but few countries could withstand the amount of pressure China would exert to dominate Diego Garcia entirely.

I have yet to hear a compelling reason as to why the British people should cut ties with the Chagos Islands. In fact, the entire deal with Mauritius only came to fruition because the United Nations’ kangaroo court issued a non-binding advisory opinion to shame the United Kingdom for its presence in the Indian Ocean.

At a time when our adversaries in Russia, China, and Iran are testing the true strength of our military alliances, we cannot allow a United Nations smear campaign against the British people and their territories become yet another fissure in the special relationship that Americans and Britons share.

Fortunately, the United Kingdom has time to work with the Trump administration to halt this deal and ensure that the Chagos Archipelago remains a British territory. The Prime Minister can remind the American people why they have so much faith in our British allies by standing strong against the United Nations and protecting our shared national security interests on Diego Garcia.

John Kennedy is a US Senator for Louisiana. This piece originally appeared at The Telegraph (UK).