The thaw in U.S.-Cuba relations continued Saturday at the 35-nation Summit of the Americas when President Obama met face-to-face with his Cuban counterpart, President Raul Castro.

There was plenty of substance behind the symbolic handshake photo op, and the diplomatic impact could extend to the rest of the hemisphere. Challenges lie ahead, but if Obama is eventually successful in re-establishing normal diplomatic relations with Cuba, there will likely be benefits for the U.S. throughout the region.

This diplomatic dividend was already on display in Panama City, site of the summit. Obama, and by extension, the U.S., was received much more warmly than at previous meetings, when the United States was able to keep Cuba sidelined. This year, Cuba was present. Absent, however, was the chronic carping about U.S. policy toward the region. This not only is important for U.S. hemispheric relations but also removes a convenient scapegoat for regimes that are repressing their people or thwarting economic growth, or both. Indeed, Obama may be able to rightly position the U.S. as being not the problem but rather a partner to a region sorely in need of political and economic reform.

That's a view seemingly shared by many diplomats, including Ambassador Carla Hills, a former U.S. trade representative who received the Economic Club of Minnesota's 2015 Bill Frenzel Champion of Free Trade Award on Monday.

"We have been widely criticized in Latin America because we objected and didn't want Cuba to be invited, and they [other summit participants] wanted to have holistic Latin American participation," Hills told an editorial writer. Now, with that no longer an issue, Hills urged that Latin American nations "get on with the real issues: trade, security, economic benefits, education and how we can work together. We could make this hemisphere the most competitive in the world."

That possibility would bring benefits to the U.S. and other nations, and shouldn't be held hostage by a failed 50-plus-year policy that only ensconced the Castro regime in power. "The Cold War has been over for a long time," Obama said. "I'm not interested in having battles frankly that started before I was born."

Obama should act on his pledge to press Havana on human rights, free speech and reform. U.S. policy shifts that can help spur change shouldn't be automatic, including the decision on whether to remove Cuba from the U.S. list of state sponsors of terrorism, which Obama will rule on soon. As for Congress, it will have a say on eventually lifting U.S. sanctions on Cuba. But clearly engagement, not isolation, is the best method to effect change.

"Over time, it is possible for us to turn the page and develop a new relationship between our two countries," Obama said. If that possibility is realized, it may not just be the two countries, but the entire Western Hemisphere, that benefits.