It has long been feared ^[1] that Cambodia’s growing dependence on China—its largest aid donor, investor and creditor—would lead to a Chinese military presence in the country. According to a recent Wall Street Journal report ^[2], those fears are now coming true.

Like a gambler reliant on a loan shark, Cambodia has, in recent years, racked up massive, opaque debts to China that it cannot repay. This has given China considerable leverage, enabling it, for example, to evade ^[3] US President Donald Trump’s trade tariffs, by rerouting exports to the United States through Cambodia’s Chinese-owned Sihanoukville Special Economic Zone.

Judging by China’s history ^[4] of ‘debt-trap diplomacy’, it was only a matter of time before it used its leverage over Cambodia to strengthen its regional military posture. According to the Wall Street Journal, the time came this spring, when China and Cambodia secretly signed an agreement giving China exclusive rights to a part of Cambodia’s Ream naval base on the Gulf of Thailand.

Both the Chinese and Cambodian governments deny ^[5] the report, which Cambodian Prime Minister Hun Sen called ‘made up’ and ‘baseless’. But that should be no surprise: as Hun Sen noted, hosting foreign military bases is illegal in Cambodia, according to the 1991 Paris Peace Agreements that ended its long civil war. Furthermore, as the US Department of State has pointed out ^[5], Cambodia has a constitutional commitment to its people to maintain a neutral foreign policy.

For Hun Sen, however, there’s good reason to disregard this commitment: his political survival. The Cambodian people, including the military, are fed up with the authoritarian and corrupt leadership ^[6] of the world’s longest-serving prime minister. The regime has so far countered this resistance by cracking down ^[7] on dissent. In last year’s sham election, Hun Sen’s Cambodian People’s Party won every seat in the parliament, after dissolving ^[8] the leading opposition party, the Cambodia National Rescue Party (of which I am co-founder and acting leader).

Hun Sen knows that, as a compliant ally of China, he gains powerful protection from hostile domestic forces. That outcome, he seems to have calculated, is worth more than the support of the Cambodian people, many of whom resent China’s growing commercial presence, which benefits ^[9] only a corrupt elite.

Hun Sen’s effort to buttress his regime will come at a heavy cost, and not just to Cambodians. The Ream naval base will provide a convenient springboard for China to bully or even attack nearby countries, thereby enhancing its ability to assert ^[10] its territorial claims and economic interests in the South China Sea. China’s tightening control over routes through which one-third ^[11] of the world’s shipping passes raises obvious risks for the US and Europe.

Chinese dominance in the South China Sea would also go a long way towards entrenching China as a global naval superpower—a status that it has been doggedly pursuing in recent years, with investments in ports as far afield as Greece, Israel, Italy and the Horn of Africa. China has used its first overseas military base, in Djibouti, to gather intelligence on US forces in the region and, the Pentagon alleges, to blind ^[12] US military pilots temporarily with high-grade ground-based lasers.

The Cambodian base is particularly worrying, because it will complete a Chinese military perimeter around mainland Southeast Asia, raising the spectre of a new ‘iron curtain’ that leaves the entire region under China’s thumb. During the Cold War, the ‘domino theory’ held that if one country fell under the influence of communism, the surrounding countries would soon follow. China—far wealthier, shrewder and more sophisticated than the Soviet Union ever was—is dangerously well equipped to make that a reality.

As the military analyst Charles Edel has argued ^[10], Pakistan, Sri Lanka and Vanuatu all have the potential for deep-water ports that could serve Chinese naval expansion and restrict Western access to key parts of the Indian and Pacific Oceans. Already, China has courted all three countries with long-term financial aid packages.

But China’s dangerous expansionism is neither inevitable nor unstoppable: it depends on compliant local regimes and inaction on the part of the international community. In the case of Cambodia, the international community should demand a new general election that doesn’t exclude real challengers. Through a credible democratic process, the Cambodian people could replace Hun Sen’s anachronistic regime with one that respects the rule of law and defends their interests—beginning by rejecting any deal that allows China to entrench its military in Cambodia.