In 1915, the US Marines invaded Haiti, occupying the country until 1934. US officials rewrote the Haitian constitution, and when the Haitian national assembly refused to ratify it, they dissolved the assembly. They then held a "referendum" in which about 5% of the electorate voted and approved the new constitution – which conveniently changed Haitian law to allow foreigners to own land – with 99.9% voting for approval.

The situation today is remarkably similar. The country is occupied, and although the occupying troops wear blue helmets, everyone knows that Washington calls the shots. On 28 November an election was held in which the country's most popular political party was excluded; but still the results of the first round of the election were not quite right. The OAS – under direction from Washington – then changed the results to eliminate the government's candidate from the second round. To force the government to accept the OAS rewrite of the results, Haiti was threatened with a cutoff of aid flows – and, according to multiple sources, President Préval was threatened with being forcibly flown out of the country – as happened to President Jean-Bertrand Aristide in 2004.

Now, Aristide has been issued a diplomatic passport by the government, and is preparing to return. But Washington does not agree, as US state department spokesman PJ Crowley made clear this week. He was also asked if the US government had pressured either the Haitian or South African governments to prevent Aristide's return. He refused to answer; I take that as a "yes".

The United States has been the prime cause of instability in Haiti, not only over the last two centuries, but the last two decades. Although Haiti is a small and poor country, Washington still cares very much about who is running it – and as leaked WikiLeaks cables recently demonstrated, they want a government that is in line with their overall foreign policy for the region. In 1991, Aristide Haiti's first democratically elected president was overthrown after just seven months in office. The officers who carried out the coup and established the military government, killing thousands of innocent Haitians, were subsequently found by the New York Times to be in the pay of the US Central Intelligence Agency (CIA).

When Aristide was elected to a second term, in 2000, the United States and its allies destroyed the economy through an economic aid cutoff. Together with aid to the Haitian opposition and an armed insurrection, Washington's effort succeeded in overthrowing the government four years later.

Now that Aristide is returning, we can expect to see a massive smear campaign again against him in the mainstream media, with allegations of human rights abuses and "moral equivalence" comparisons with the Duvalier dictatorships. In his book, Damming the Flood, Professor Peter Hallward looks at the best available data for the number of political murders in Haiti: Duvalier dictatorships (1957-1986): 50,000; after the US-sponsored coup of 1991 (with US-funded death squads): 4,000; after the US-organised coup of 2004: 3,000; Aristide's tenure in office (2001-2004): between 10 and 30.

Aristide eliminated more than 98% of the political violence in Haiti by abolishing the army and the murderous "section chief" system, which were the main sources of political violence. For that, Washington will not forgive him. And for that, Orwellian media outlets portray him as a dictator.

Can the US and its allies continue to deny Haiti's national sovereignty, which it won 207 years ago in the world's first successful slave revolt? This is, after all, why they overthrew Aristide twice and seek to prevent his return. He is still a symbol of Haiti's sovereignty, and respect for the poor, for millions of Haitians. For Washington, that is inherently dangerous.

But the Americas have changed since the last time Aristide was overthrown. Washington met strong resistance from South America when it supported the coup government in Honduras in 2009; Honduras has still not been allowed back into the OAS. Governments that Washington did not want – for example, in Bolivia, Ecuador and Venezuela – have been elected and survived despite coup attempts and other destabilisation efforts that were sometimes supported by the United States. This would not have happened 15 years ago. The left governments that now preside over the majority of Latin America have dramatically and permanently changed hemispheric relations.

Last week, Washington failed to get support for its change of Haiti's election results in both the OAS and the 23-nation Rio Group. Unfortunately, Brazil has supported Washington in heading up the UN occupying force in Haiti; but this will not go on indefinitely, especially if they are called upon to shoot people who are demanding their basic democratic rights.

These rights can no longer be denied to Haitians, simply because they are poor and black. Nor can Aristide be denied the right to return to his country. Washington will have to adapt to a new reality, as it is discovering in Egypt.

Article by Mark Weisbrot in the Guardian Comment is Free