WASHINGTON — President Barack Obama’s decision to pursue new relations with Cuba was driven in part by a stinging realization: Longstanding U.S. policies aimed at isolating Cuba had instead put Washington at odds with the rest of the world.

The American economic embargo on Cuba drove a wedge between the U.S. and Latin American nations. In an annual diplomatic embarrassment, the United Nations General Assembly votes overwhelmingly to condemn the U.S. policy. And while the U.S. was clinging to its economic restrictions against the small communist nation just 90 miles off its shores, leaders of China, Russia and Brazil flocked to Havana, promising millions in investment.

“Though this policy has been rooted in the best of intentions, no other nation joins us in imposing these sanctions, and it has had little effect beyond providing the Cuban government with a rationale for restrictions on its people,” Obama said Wednesday as he announced historic shifts in U.S. relations with Cuba following 18 months of secret negotiations.

The embargo itself will remain in place; only Congress can fully revoke it. But the president is moving on his own to expand economic ties, open an embassy in Havana, send high-ranking U.S. officials including Secretary of State John Kerry to visit and review Cuba’s designation as a state sponsor of terrorism. The U.S. also is easing restrictions on travel to Cuba, including for family visits, official government business and educational activities. Tourist travel remains banned.

For the president, the moves signaled his willingness to stretch his executive authority to remake American foreign policy without Congress. As he enters the waning years of his presidency, Obama is increasingly flexing his presidential powers not only on U.S.-Cuba policy, but also on immigration, Internet neutrality and climate change.