WASHINGTON — The U.S. government on Thursday tentatively approved scheduled commercial airline service to Havana from 10 American cities, further bridging the gulf between countries as close as an hour flight but long kept at a greater distance by the Cold War.

The decision is another long stride in President Obama’s effort to normalize U.S.-Cuba relations.

“Reopening travel relations with Cuba is about more than just restoring the freedom to travel there for all Americans – it’s about opening Cuba to new ideas, new values and improved human rights that our 50-year-old policy of isolation could not achieve,” said Sen. Dick Durbin, D-Ill.

But Rep. Jeff Duncan, R-S.C., chairman of the House Committee on Foreign Affairs’ Subcommittee on the Western Hemisphere, expressed doubts about the Cuban government’s ability to prevent attacks by militants, saying the Obama administration is “in a mad rush to sign agreements” before “ensuring basic safeguards of security.”

Eight U.S. airlines are expected to begin round-trip service as early as this fall between the U.S. and the Cuban capital, Transportation Secretary Anthony Foxx said.

The U.S. cities are Atlanta; Charlotte, North Carolina; Houston; Los Angeles; Newark, New Jersey; New York; and four in Florida – Miami, Fort Lauderdale, Orlando and Tampa. Of the 20 daily nonstop flights allowed to Havana, 14 are from Florida, home to the largest population of Cuban-Americans.

The airlines are Alaska, American, Delta, Frontier, JetBlue, Southwest, Spirit and United.

A year and a half ago, Obama announced with Cuba President Raul Castro that it was time for the longtime adversaries to “begin a new journey.” Washington has since reopened the U.S. Embassy in Havana and taken other steps to bolster ties.

Conservatives in Congress have been unwilling to lift the trade embargo of Cuba, which includes a travel ban. That means most Americans still cannot legally visit Cuba. But the administration has eased rules to the point where travelers are now free to design their own “people-to-people” cultural exchange tours with little oversight. Cuban-Americans have been able to travel to Cuba without restriction since 2009.