A journalist from a party of former Marxist guerrillas became El Salvador's first leftist president, promising to remain friendly with the United States while immediately restoring ties with Cuba.
Mauricio Funes brought to power the Farabundo Marti National Liberation Front that fought for 12 years to overthrow US-backed governments until laying down their arms in 1992.
But he sought to ease fears of radicalism by comparing himself to US President Barack Obama as well as Brazil's Luiz Inacio Lula da Silva, a leftist who has maintained warm ties with leaders across the political spectrum.
"We turned to the strong examples of Obama and Lula as proof that progressive leaders - instead of being a threat - can be a new, safe alternative for their people," Funes said in his inaugural address.
Members of his party applauded wildly and shouted the traditional chant of the left in Latin America: "The people united will never be defeated!"
Plucked from outside the party ranks, the bespectacled television journalist won the March 15 elections by helping the movement shed a radical image that alienated many Salvadorans scarred by civil war.
During a bitter electoral campaign, critics branded Funes a communist and compared him to Venezuela's Hugo Chavez and Nicaragua's Daniel Ortega, leaders who delight in denouncing the United States.
Funes avoided meeting Chavez during the campaign, though he said he would maintain respectful relations with him. Both Chavez and Ortega cancelled plans to attend the inauguration at the last minute and did not state why.
Obama sent Secretary of State Hillary Rodham Clinton to represent the United States at the inauguration, which she called a testament to the strength of democracy in the Americas.
Funes singled her out in his inaugural speech as a "woman who honours America and radiates the brilliance of the feminine gender throughout the world."
After the inauguration, Clinton said the United States wants to improve relations in Latin America.
"We have to recognise that our country is not perfect either, that some of the difficulties that we had historically in forging strong and lasting relationships in our hemisphere are a result of us perhaps not listening, perhaps not paying enough attention," she told US Embassy employees.
Funes, 49, replaced President Tony Saca, whose staunchly conservative government was one of the most steadfast U.S. allies in the region - the last to pull its troops from Iraq earlier this year.
But El Salvador will no longer routinely endorse US policies unpopular in the region.
Funes announced he was restoring ties with "the sister nation of Cuba," leaving the United States as the last country in the Western Hemisphere with no formal relations with the communist-governed island. On Tuesday, the 34 countries in the Organisation of American States meet in Honduras to consider ending Cuba's 50-year-old suspension from the group.
Obama has signaled willingness to ease US hostility toward Cuba, but his administration says it will not support efforts to get Cuba back into the OAS until it makes political changes.
Funes consolidates a leftward shift across Latin America, especially in Central America, where Sandinista leader Ortega returned to Nicaragua's presidency in 2006, two decades after his Sandinista government fought US-backed Contra rebels.
Left-of-centre presidents also govern Guatemala and Honduras.
Funes rose to prominence as a TV host outspoken about corruption and he has no governing experience. He inherits an economic recession, widespread gang violence, and a population bitterly polarised over his party's rise to power.
Funes has promised fiscal austerity while raising funds for education and health care by cracking down on tax evasion.
He will have to compromise both with more radical members of his party and with the outgoing Arena party, which will have enough seats in the single-house Congress to block key measures such as the budget and foreign debt approvals.
Funes said he will not "have the luxury of making mistakes" like his predecessors by "governing for few, being complacent about corruption, accomplices of organised crime."
Before his inauguration, Funes visited the grave of Archbishop Oscar Romero, whose 1980 assassination was one of the more shocking events in a civil war between a US-backed government and leftist guerrilla fighters backed by Cuba and the Soviet Union. More than 75,000 people were killed before fighting ended in 1992.
AP