President Obama announced the opening of embassies in Cuba and the United States, formally beginning the process to establish diplomatic relations with the communist island nation after 54 years of American isolation.

"This is a historic step forward in our efforts to normalize relations with the Cuban government and people and begin a new chapter with our neighbors in the Americas," Obama said in a statement in the Rose Garden with Vice President Joe Biden at his side.

"This is what change looks like," he said later in his remarks, referring Secretary of State John Kerry's plans to travel to Cuba later this summer and hoist the American flag above the U.S. embassy in Havana.

The president vigorously defended the move to open the embassies and try to normalize diplomatic and economic relations with Havana against detractors who argue that doing so is only appeasing the Castro regime, which regularly imprisons democracy activists and refuses to all free and fair elections.

When the United States shuttered its embassy in Havana at the height of the Cold War in 1961, Obama said he didn't believe that anyone expected that it would be a half century before it re-opened.

Despite the short distance and the deep bonds between the United States and Cuba in the form of family ties and friendships, he said the United States has clung to a policy that is not working and has allowed itself to "trapped by a certain way of doing things."

Even though the U.S. attempt to isolate Cuba was based on good intentions to try to move the Cuban government to become more open to democratic reforms, the president argued that the move backfired.

"[It] increasingly had the opposite effect, cementing the status quo and isolating the United States from our neighbors in this hemisphere," he said.

Characterizing the re-opening of ties with Cuba as "progress," he said it shows that the U.S. doesn't have to be "imprisoned in the past."

"When something isn't working, we can and will change," he asserted, stressing that the best way for Americans to extend our values of freedom and democracy is through engagement.

He also claimed the American public is on his side, citing polls showing that the majority of the U.S. and Cuban public support his decision to re-open ties.

He said opponents of his decision want to "turn back the clock" and "doubled-down" on an approach that doesn't work and has only shut America out of Cuban's future and made life worse for the island's people.

Vocal critics of the policy, including several Cuban-American lawmakers, have argued just the opposite — that Obama is making too many concessions to the Castro regime without any guarantees of greater openness and or democratic reforms, such as free and fair elections.

Sen. Marco Rubio, R-Fla., earlier Wednesday pledged to oppose any Obama nominee to become ambassador to Cuba.

"It is time for our unilateral concessions to this odious regime to end," he said in a statement released Wednesday morning.

For example, Rubio said the Obama administration has done nothing to secure the return of U.S. fugitives the Castro regime is harboring in Cuba, settle outstanding legal claims to U.S. citizens for properties confiscated by the regime, or secure "unequivocal" assurances that our diplomats will be able to travel freely throughout Cuba and meet with dissidents.