The Trump administration’s Monroe Doctrine inspired pursuit of a sphere of hegemonic influence in the Western hemisphere faces the vulnerability that it has left the entry point to the South Atlantic, the literal backdoor to that sphere, unguarded.
A naval base at Simonstown in South Africa guards the gateway from the Indian Ocean to the South Atlantic. Simonstown’s naval history dates to the 1700s when as a Dutch anchorage and later a British base it commanded the sea route from Asia to Europe. The base was influential in the definitive naval exchanges of the First and Second World Wars which took place in the South Atlantic and determined control of the North Atlantic and thereby the outcome of both conflicts. In 1982 Britain’s earlier ceding of the base to South Africa caused great logistical difficulties for the naval taskforce sent by Mrs Thatcher to retake the Falklands. During the Cold War the Soviet Union was very concerned that South Africa’s submarines might sink its vessels supplying Africa’s hot wars.
Simonstown’s contemporary importance is best understood as one of three points of a triangle that determines the balance of power in the Indo-Pacific.
That triangle is formed by drawing a 5,000 mile line northwards from Simonstown to Djibouti on the African east coast where the Bab al-Mandab Strait narrows the gateway into the Red Sea (and the Suez Canal beyond) to just 20 miles. The balance of power around that gateway shifted in 2016 when China was granted a lease on a naval base just more than a decade after the United States had secured a similar lease.
From Djibouti extend the line 8,000 miles eastward to the Solomon Islands off the east coast of Australia. The Japanese, after crippling the US Pacific Fleet at Pearl Harbor, sought to occupy the islands to isolate Australia and their retaking was a key allied objective in the liberation of South-East Asia. However, in April of 2022, eight decades after the defeat of Japan, China signed a security pact with the Solomon Islands. As the islands lie east of the confines of the two major “island chains” around which John Foster Dulles’ Pacific containment strategy was conceived at the end of the Second World War the Chinese pact is the starkest challenge yet to the idea of the Pacific as “America’s lake”.
Extend the line from the Solomon Islands back to Simonstown to complete the triangle and territory within sees the passage of more than half of all sea-borne global trade with the triangle’s three points determining access to the Red Sea, the South Atlantic, and the Pacific.
Exacerbating American vulnerability in the Indo-Pacific is that at the triangle’s center is the Chagos Islands archipelago which Britain sought to surrender to Mauritius in October 2024. The archipelago contains the island of Diego Garcia which houses a US naval base (leased from Britain). Flying from Diego Garcia nuclear armed American aircraft can reach Australia, the southern and eastern regions of China, the southern points of eastern Europe, and much of the Middle East.
Whilst the British government provided assurances that the US might strike terms to continue operating from Diego Garcia this is not at all assured and the Trump administration has therefore moved swiftly to force a British about-turn. Mauritius is a signatory to an African nuclear weapons ban which may be employed as a pretext to undermine American activities on the island. The island has also been secured by a “marine protected zone” to keep foreign spy ships at bay, but Mauritius, in looking to exploit the commercial potential of the archipelago, may open its waters to commercial fishing fleets which often serve as the maritime eyes and ears of their host nations’ intelligence services.
The extent to which America achieves a Monroe Doctrine inspired sphere of hegemonic influence in the Western hemisphere will be determined in part by whether backdoors into that envisaged sphere are left unguarded. The vulnerability at the Solomon Islands might be addressed from Guam and Hawaii whereas the Mediterranean presents a hard obstacle to China’s aims of reaching the Atlantic. Diego Garcia might yet be saved. That leaves South Africa’s Simonstown as the key external vulnerability. South Africa’s foreign policy is in flux. As the briefly unipolar post-Cold War era morphed into a multipolar one South Africa’s government deepened its ties with Russia, China, and Iran. However, last year South Africa’s once dominant ruling party lost its political majority and entered into a coalition with a chiefly Western allied opposition party. Should that coalition collapse it may be supplanted by one strongly allied against the United States. Amidst heightened diplomatic tensions between South Africa and the Trump Administration the effect would be to allow America’s enemies an open door to the South Atlantic.
Dr Cronje heads the Washington DC-based Yorktown Foundation for Freedom. Rear Admiral Higgs (Ret) commanded the Fleet of South Africa from 2008-2010 and served as Chief of Naval Staff from 2011 to 2016. He completed the Naval Command College Course of the United States Naval War College in 1995.
