On Monday, six days after the earthquake in Haiti, the US Southern Command finally began to drop bottled water and food from an air force C-17. US defence secretary Robert Gates had previously rejected such a method because of "security concerns".

If people do not get clean water, there could be epidemics of water-borne diseases that could greatly increase the death toll. But the US is now sending 10,000 troops and seems to be prioritising "security" over much more urgent, life-and-death needs. This in addition to the increase of 3,500 UN troops scheduled to arrive.

On Sunday morning the world-renowned humanitarian group Doctors Without Borders complained that a plane carrying its portable hospital unit was re-routed by the US military through the Dominican Republic. This would cost a crucial 48 hours and an unknown number of lives.

On Sunday, Jarry Emmanuel, air logistics officer for the UN's World Food Programme, said: "There are 200 flights going in and out every day, which is an incredible amount for a country like Haiti ... But most flights are for the US military."

Yet Lieutenant General PK Keen, deputy commander of the US Southern Command, reports that there is less violence in Haiti now than there was before the earthquake hit. Dr Evan Lyon, of Partners in Health, a medical aid group famous for its heroic efforts in Haiti, referred to "misinformation and rumours … and racism" concerning security issues.

We've been circulating throughout the city until 2:00 and 3:00 in the morning every night, evacuating patients, moving materials. There's no UN guards. There's no US military presence. There's no Haitian police presence. And there's also no violence. There is no insecurity.

To understand the US government's obsession with "security concerns," we must look at the recent history of Washington's involvement there.

Long before the earthquake, Haiti's plight has been comparable to that of many homeless people on city streets in the US: too poor and too black to have the same effective constitutional and legal rights as other citizens. In 2002, when a US-backed military coup temporarily toppled the elected government of Venezuela, most governments in the hemisphere responded quickly and helped force the return of democratic rule. But two years later, when Haiti's democratically elected president Jean-Bertrand Aristide was kidnapped by the US and flown to exile in Africa, the response was muted.

Unlike the two centuries of looting and pillage of Haiti since its founding by a slave revolt in 1804, the brutal occupation by US marines from 1915 to 1934, the countless atrocities under dictatorships aided and abetted by Washington, the 2004 coup cannot be dismissed as "ancient history." It was just six years ago, and it is directly relevant to what is happening there now.

The US, together with Canada and France, conspired openly for four years to topple Haiti's elected government, cutting off almost all international aid in order to destroy the economy and make the country ungovernable. They succeeded. For those who wonder why there are no Haitian government institutions to help with the earthquake relief efforts, this is a big reason. Or why there are 3 million people crowded into the area where the earthquake hit. US policy over the years also helped destroy Haitian agriculture, for example, by forcing the import of subsidised US rice and wiping out thousands of Haitian rice farmers.

Aristide, the country's first democratically elected president, was overthrown after just seven months in 1991, by military officers and death squads later discovered to be in the pay of the CIA. Now Aristide wants to return to his country, something that the majority of Haitians have demanded since his overthrow. But the US does not want him there. And the René Préval government, which is completely beholden to Washington, has decided that Aristide's party – the largest in Haiti – will not be allowed to compete in the next elections (originally scheduled for next month).

Washington's fear of democracy in Haiti may explain why the US is now sending 10,000 troops and prioritising "security" over other needs.

This military occupation by US troops will raise other concerns in the hemisphere, depending on how long they stay – just as the recent expansion of the US military presence in Colombia has been met with considerable discontent and distrust in the region. And non-governmental organisations have raised other issues about the proposed reconstruction: understandably they want Haiti's remaining debt cancelled, and grants rather than loans (the IMF has proposed a $100m dollar loan). Reconstruction needs will be in the billions of dollars: will Washington encourage the establishment of a functioning government? Or will it prevent that, channelling aid through NGOs and taking over various functions itself, because it of its long-standing opposition to Haitian self-rule?

But most urgently, there is a need for rapid delivery of water. The US air force has the capability to deliver enough water for everyone who needs it in Haiti, until ground supply chains can be established. The more water is available, the less likely there is to be fighting or rioting over this scarce resource. Food and medical supplies could also be supplied through air drops. These operations should be ramped up, immediately. There is no time to lose.