The U.S. government today called the overthrow of Honduran President Manuel Zelaya, "illegal" and "illegitimate" and it is calling for Zelaya to be returned to his country.
In a statement, President Obama said he was "deeply concerned" about the situation and he called on "all political and social actors in Honduras to respect democratic norms, the rule of law and the tenets of the Inter-American Democratic Charter. Any existing tensions and disputes must be resolved peacefully through dialogue free from any outside interference."
Tanks rolled into the Honduran capital city of Tegucigalpa today and soldiers seized the national palace, just hours before the country was to hold a constitutional referendum.
Zelaya had orchestrated the vote in hopes of changing the law to allow him to stand for re-election, which is prevented by term limits in Honduras.
The country's supreme court had ruled the referendum illegal and congress -- as well as Zelaya's own political party members -- had opposed it. But Zelaya had pushed forward despite widespread opposition.
Zelaya is a close ally of leftist Venezuelan President Hugo Chavez, who has become a unifying force for strong, leftist political movements in Latin America.
In response to Zelaya's ouster and alleged threats to Venezuela's envoy in Honduras, Chavez said his country is "at battle" and said he would not hesitate to use military intervention if necessary.
Roger Noriega, the former U.S. Assistant Secretary of State for the Western Hemisphere, said Zelaya underminded his own government's institutions and now those institutions aren't there to protect him.
"No one should applaud an illegal interruption of power. I don't think coups are good for institutions in the Americas and you need institutions to have stability and justice in these countries. Having said that, Zelaya was attacking these institutions," Noriega said. "The lesson I think we should get from this is that these populist strongmen really need to play by the rules."
The Honduran congress was quick to replace Zelaya. Just hours after the coup, lawmakers signed a resolution accusing Zelaya of "manifest irregular conduct" and "putting in present danger the state of law."
By a show of hands, the congress voted to officially remove Zelaya from office and they swore in his successor, Roberto Micheletti as the new head of state.
But the decision may not stand. The Organization of American States (OAS) met in Washington today and released a statement denouncing the coup and calling for "the immediate, safe and unconditional return of the constitutional president, Manuel Zelaya."
U.N. Secretary-General Ban Ki-moon also condemned the coup and said through his spokeswoman, Michele Montas that he "urges the reinstatement of the democratically elected representatives of the country."
U.S. State Department officials today said the American government does not recognize Micheletti as the new leader of Honduras.
Neither do protesters who took to the streets today in Honduras, marching outside the presidential palace, holding signs, demanding that Zelaya be returned to power.
The Honduran ambassador to the OAS, Carlos Sosa, said the country was in chaos.
"Right now there is no water, no power, no electricity and the local Honduran TV cannot broadcast," Sosa said.
The U.S. permanent representative to the OAS, Hestor Morales, underscored Obama's message.
"We are here in a sign of support for the priniciples of democracy," he said. "We want to make sure that constitutional order is maintained, that the rule of law is respected."
Honduras has a history of military coups and regional experts say this latest takeover is a difficult test for the country's tenuous democracy.
The United States has 600 troops stationed at Soto Cano Air Base, a Honduran military installation an hour's drive from Tegucigalpa. The base is a headquarters for a regional U.S. task force involved in drug interdiction, which also provides humanitarian assistance in the region.
A Pentagon spokesman said things are quiet and calm for the time being and that commanders on the ground are taking appropriate force protection measures.
Meanwhile, the U.S. embassy in Tegucigalpa warned American citizens in Honduras to remain indoors until the protests have died down and order has been restored.
Local media reports say that Zelaya, who the Honduran military had flown to Costa Rica, is now making his way to Nicaragua where he's expected to meet with OAS officials later in the week.
ABC News' Kirit Radia and Arlette Saenz contributed to this report.