Raul Castro has taken over as president of Cuba, ending his brother Fidel Castro's 49-year rule.
Raul Castro, 76, was confirmed as the new president by Cuba's National Assembly this afternoon.
The Cuban government will continue consulting the ailing Fidel Castro on major decisions of state, Raul Castro said.
He also vowed to be on guard against US 'meddling'.
'We have taken note of the offensive and openly meddling declarations by the empire and some of its closest allies,' the new Cuban leader said.
In a surprise move, orthodox Communist Party ideologue Jose Ramon Machado Ventura, 77, who fought alongside the Castro brothers in their 1950s revolution, was chosen for the deputy leader post as first vice president.
Commentators had expected the deputy leader post to go to 56-year-old Carlos Lage, who drew up limited economic reforms in the 1990s. Mr Machado's nomination suggests change is unlikely to be deep or abrupt.
Raul Castro has led the West's last communist state since July 2006 when long-time US foe Fidel Castro temporarily handed over power after undergoing intestinal surgery. The bearded revolutionary officially retired on Tuesday.
Analysts expect that Raul Castro will introduce limited reforms to kickstart the state-run economy in this Caribbean nation, where most people live in tumbledown houses and struggle to find enough to eat.
Fidel Castro, who once gave seven-hour speeches under the Caribbean sun, has not appeared in public since undergoing intestinal surgery in July 2006.
He said he was too weakened by his undisclosed illness to continue governing but would soldier on in the 'battle of ideas' by writing articles.
He will retain significant but potentially waning influence as first secretary of the ruling Communist Party.
Anti-Castro exiles and US President George W Bush have led calls for democratic reform on the island. But in the streets of the capital, Havana, the mood is more of indifference than expectation of political changes.
Few think that with Fidel Castro gone the West's last communist state will crumble swiftly like many Soviet allies did.
Some of his staunchest supporters think he is still the unquestionable 'leader of the revolution' and will continue pulling the strings of power.
Raul Castro is considered a manager more concerned with putting food on Cuban tables than waging an ideological war against the US.
As acting president, Raul Castro has fostered debate on the failings of Cuba's state-run economy and raised expectations that reform may be coming. In December he stated that Cuba has 'excessive prohibitions'.
But so far he has delivered little other than relaxing customs rules for appliances and car parts that are much in demand, and desperately short in supply, in Cuba.
Many Cubans hope they will soon be allowed to freely buy and sell their homes, travel abroad and stay at hotels and beaches where only foreigners can now set foot.
Last year, Raul Castro extended an olive branch to the US, saying he was open to talks but only after President George W Bush, who tightened economic sanctions and travel restrictions to Cuba, leaves office.
Bush administration officials rejected the offer, calling Raul Castro 'Fidel Lite' and denouncing what they see as the handing of power from one dictator to another.