Explainer: Where is Diego Garcia & Why It Is Strategically Important Military Base?

The article examines the sovereignty transfer of the Chagos Islands, including Diego Garcia, the proposed 100-year lease to Mauritius, and the implications for US-UK military cooperation and regional security in the Indian Ocean.

Diego Garcia, a remote island in the Indian Ocean, is drawing sharp global focus after US President Donald Trump warned the United Kingdom against "losing control" of it. The island hosts a major US-UK military base and sits at the centre of talks involving the UK and Mauritius over future control and a long-term lease arrangement.

Under a proposal supported by London and Port Louis, Britain plans to transfer sovereignty of the wider Chagos Islands to Mauritius. The UK would then lease Diego Garcia back for 100 years, keeping the base operational. Over that lease period, British officials expect the arrangement to cost London around £35 billion.

Diego Garcia military base and Indian Ocean security

At the core of the deal is the Diego Garcia military base, one of the most strategic in the world. The facility is a joint US-UK installation, used for bomber operations, naval missions, surveillance flights and logistics support. Its position in the Indian Ocean lets the US deploy assets swiftly across the Middle East, Africa and large parts of Asia.

During the wars in Afghanistan and Iraq, long-range US bombers flew from Diego Garcia to conduct strike missions. Even in the present security climate, the base helps monitor tensions in the Middle East and the Indo-Pacific region. For India, especially states like Uttar Pradesh linked to global trade and workforce routes, stability in these waters is closely watched.

Where is Diego Garcia?

Diego Garcia is the largest island in the Chagos Archipelago, located in the central Indian Ocean.

It lies roughly:

• 1,800 km south of India
• 2,200 km east of Africa
• 4,700 km west of Australia

The island is extremely isolated, with no civilian population. It is controlled by the UK as part of the British Indian Ocean Territory.

However, Mauritius claims sovereignty over the Chagos Islands, saying they were illegally separated during colonial rule.

Diego Garcia, Chagos Islands dispute and Trump’s warning

Diego Garcia lies within the Chagos Archipelago, about 1,800 kilometres south of India, inside the British Indian Ocean Territory. Mauritius argues the islands were unlawfully separated from its territory during colonial rule and has long pressed its claim. Britain has now agreed in principle to recognise Mauritian sovereignty over the Chagos Islands, while maintaining defence use through the lease.

Trump publicly criticised this plan in a social media post aimed at British Prime Minister Keir Starmer. Trump warned that leasing the base from Mauritius would be a "big mistake," and branded the arrangement "tenuous at best." Trump argued the base could be vital if any future military action against Iran became necessary, and said the UK should avoid weakening its control.

Trump’s intervention surprised many observers because the US government had already supported the UK-Mauritius agreement. The sharp comments triggered political argument inside Britain, with opposition figures calling the situation embarrassing for the government. Officials, however, defended the proposal, saying it was the only realistic way to secure the base’s long-term operation under international pressure.

Why Diego Garcia is strategically important

Despite being tiny, Diego Garcia is one of the most important military bases in the world.

1. US military's key Indian Ocean base

The island hosts a major joint US-UK military base.

It is used for:

• Long-range bomber operations
• Naval deployments
• Surveillance missions
• Pre-positioning of weapons and supplies

The base allows the US to project military power across:

• Middle East
• Africa
• South Asia
• Indo-Pacific region

This includes areas like Iran, Afghanistan, Iraq, and even parts of China's sphere of influence.

Trump himself said the base could be used to launch attacks against Iran if needed.

2. Crucial location advantage

Diego Garcia sits at a strategic midpoint between three continents:

• Asia
• Africa
• Australia

Because of this, military aircraft and ships can quickly reach conflict zones.

It played major roles in:

• Gulf War (1991)
• Afghanistan War (2001)
• Iraq War (2003)

US bombers like B-52 and B-2 operated from here.

3. Countering China's growing presence

China has rapidly expanded its military footprint in the Indian Ocean.

Diego Garcia is seen as America's key counter-balance to China.

It helps monitor:

• Chinese naval movements
• Shipping lanes
• Military activity

What is the current UK-Mauritius deal?

The UK is planning to transfer sovereignty of the Chagos Islands to Mauritius.

But under the deal:

• UK would lease Diego Garcia base for 100 years
• Lease cost: £35 billion

This means Mauritius would technically own the land, but UK and US would continue using the military base.

Britain says this guarantees long-term security of the base.

Why this matters globally - and for India

Diego Garcia is extremely important for global power balance.

For India, it is significant because:

• It is located close to India's strategic sphere
• It affects Indian Ocean security
• It influences China-US rivalry in the region

India itself is expanding its naval presence due to growing Chinese activity.