When I write about US foreign policy in places such as Haiti or Honduras, I often get responses from people who find it difficult to believe that the US government would care enough about these countries to try and control or topple their governments. These are small, poor countries with little in the way of resources or markets. Why should Washington policymakers care who runs them?

Unfortunately they do care. A lot. They care enough about Haiti to have overthrown the elected president Jean-Bertrand Aristide not once, but twice. The first time, in 1991, it was done covertly. We only found out after the fact that the people who led the coup were paid by the US Central Intelligence Agency. And then Emmanuel Constant, the leader of the most notorious death squad there – which killed thousands of Aristide's supporters after the coup – told CBS News that he, too, was funded by the CIA.

In 2004, the US involvement in the coup was much more open. Washington led a cut-off of almost all international aid for four years, making the government's collapse inevitable. As the New York Times reported, while the US state department was telling Aristide that he had to reach an agreement with the political opposition (funded with millions of US taxpayers' dollars), the International Republican Institute was telling the opposition not to settle.

In Honduras last summer and autumn, the US government did everything it could to prevent the rest of the hemisphere from mounting an effective political opposition to the coup government in Honduras. For example, they blocked the Organisation of American States from taking the position that it would not recognise elections that took place under the dictatorship. At the same time, the Obama administration publicly pretended that it was against the coup.

This was only partly successful, from a public relations point of view. Most of the US public thinks that the Obama administration was against the Honduran coup, although by November of last year there were numerous press reports and even editorial criticisms that Obama had caved to Republican pressure and not done enough. But this was a misreading of what actually happened: the Republican pressure in support of the Honduran coup changed the administration's public relations strategy, but not its political strategy. Those who followed events closely from the beginning could see that the political strategy was to blunt and delay any efforts to restore the elected president, while pretending that a return to democracy was actually the goal.

Among those who understood this were the governments of Latin America, including such heavyweights as Brazil. This is important because it shows that the State Department was willing to pay a significant political cost in order to help the right in Honduras. It convinced the vast majority of Latin American governments that it was no different from the Bush administration in its goals for the hemisphere, which is not a pleasant outcome from a diplomatic point of view.

Why do they care so much about who runs these poor countries? As any good chess player knows, pawns matter. The loss of a couple of pawns at the beginning of the game can often make a difference between a win or a loss. They are looking at these countries mostly in straight power terms. Governments that are in agreement with maximising US power in the world, they like. Those who have other goals – not necessarily antagonistic to the United States – they don't like.

Not surprisingly, the Obama administration's closest allies in the hemisphere are rightwing governments such as those of Colombia or Panama, even though Obama himself is not a rightwing politician. This highlights the continuity of the politics of control. The victory of the right in Chile, the first time that it has won an election in half a century, was a significant victory for the US government. If Lula de Silva's Workers' party were to lose the presidential election in Brazil this autumn, that would be another win for the state department. While US officials under both Bush and Obama have maintained a friendly posture toward Brazil, it is obvious that they deeply resent the changes in Brazilian foreign policy that have allied it with other social democratic governments in the hemisphere, and its independent foreign policy stances with regard to the Middle East, Iran, and elsewhere.

The US actually intervened in Brazilian politics as recently as 2005, organising a conference to promote a legal change that would make it more difficult for legislators to switch parties. This would have strengthened the opposition to Lula's Workers' party (PT) government, since the PT has party discipline but many opposition politicians do not. This intervention by the US government was only discovered last year through a Freedom of Information Act request filed in Washington. There are many other interventions taking place throughout the hemisphere that we do not know about. The United States has been heavily involved in Chilean politics since the 1960s, long before they organised the overthrow of Chilean democracy in 1973.

In October 1970, President Richard Nixon was cursing in the Oval Office about the Social Democratic president of Chile, Salvador Allende. "That son of a bitch!" said Richard Nixon on 15 October. "That son of a bitch Allende – we're going to smash him." A few weeks later he explained why:

The main concern in Chile is that [Allende] can consolidate himself, and the picture projected to the world will be his success ... If we let the potential leaders in South America think they can move like Chile and have it both ways, we will be in trouble.

That is another reason that pawns matter, and Nixon's nightmare did in fact come true a quarter-century later, as one country after another elected independent left governments that Washington did not want. The United States ended up "losing" most of the region. But they are trying to get it back, one country at a time. The smaller, poorer countries that are closer to the United States are the most at risk. Honduras and Haiti will have democratic elections some day, but only when Washington's influence over their politics is further reduced.