It has said its troops will not be involved but that may be easier said than done. Several thousand Dominican soldiers have fanned out along the border for fear that thousands, even hundreds of thousands, of Haitians may try to cross if the US moves in. An influx of black French-speaking Haitians is a sensitive issue in this nation of mixed- race Spanish-speakers that came close to violence after elections in May.
President Joaquin Balaguer, 88, narrowly won the elections but was accused of fraud. He has agreed to serve only two years instead of four. Mr Balaguer, long critical of Haiti's exiled President, Jean-Bertrand Aristide, and closer to his neighbour's de facto military rulers, used the threat of the 'Haitianisation' of his country during his campaign. A black candidate of part-Haitian extraction, Jose Pena Gomez, was his main opponent. Mr Balaguer claimed Mr Pena Gomez had a secret plan, backed by the US, to unite the two halves of Hispaniola.
With Haiti's ports and airports shut down, the border with the Dominican Republic would be the only escape route for Haiti's military rulers and their cohorts. What to do with them could pose a quandary for Mr Balaguer and his armed forces, which have been working increasingly closely with US officers to prevent sanctions busting along the border.
Until recently, Mr Balaguer's acquiescence allowed Haiti's military chiefs to defy the UN-imposed sanctions by freely transporting goods across the border. The sanctions have been tightened but witnesses say fuel is still being smuggled across.
Hundreds, perhaps thousands, of Haitians are camped on their side of the ominously named Massacre river, which forms part of the border. How the Dominican armed forces can keep them out without bloodshed, following a US invasion, remains to be seen.
Aware of the sensitivity of the situation, US military officers insist the Dominican Republic will not be used as a launching pad for an invasion. But US troops on the sanctions-enforcing team have built a helicopter pad on the Dominican side of the border and set up a sophisticated communications centre, likely to be used to co-ordinate invasion strategy.
Military sources here say US invasion troops would land on the Haitian side of the border on both the Atlantic and Caribbean coasts, move inland to form a line, and then fan westwards across Haiti to take army and police posts and prevent Haitians from fleeing. These forces would eventually link up with others who had secured key installations.
One of the Dominican Republic's main concerns is for its tourist industry. Resorts such as Puerto Plata are far enough from Haiti to remain unaffected by the invasion but tourists or tour operators who may soon be seeing live CNN images of a massive US assault on the island may need some convincing.
PORT-AU-PRINCE - Haiti's military-installed President, Emile Jonassaint, appealed to the international community on Wednesday to block a US invasion in a speech that appeared to offer no compromise to Washington, Reuter reports. Mr Jonassaint gave no indication that Haiti's military leaders would accede to a US demand to stand down.