WASHINGTON — Global cooperation is needed to tackle the financial meltdown, climate change, nuclear proliferation and other pressing problems, President Obama said yesterday.

Fresh from his first trip overseas as president, Obama used his radio and Internet address to ask people in the United States and around the world to focus on areas of common interest.

"These are challenges that no single nation, no matter how powerful, can confront alone," Obama said. "The United States must lead the way. But our best chance to solve these unprecedented problems comes from acting in concert with other nations."

Obama pointed to his London meeting with leaders of the G-20 nations — a gathering that represented 85 percent of the global economy — where he pressed for increased regulation and economic stimulus. He also noted his attendance at the NATO summit in France to discuss strategy toward Afghanistan and Pakistan, as well as his speeches against nuclear weapons in the Czech Republic and about faith divisions in Turkey.

All are big-picture priorities for the young administration and most have general support among Obama's U.S. constituents.

"With all that is at stake today, we cannot afford to talk past one another. We can't afford to allow old differences to prevent us from making progress in areas of common concern," Obama said. "We can't afford to let walls of mistrust stand. Instead, we have to find — and build on — our mutual interests. For it is only when people come together, and seek common ground, that some of that mistrust can begin to fade. And that is where progress begins."

Obama used the eight-day trip to highlight his ambitious foreign policy agenda, including starting negotiations with Russia about reducing nuclear stockpiles. Such talks, announced alongside Russian President Dmitry Medvedev, would be the first in years and are part of Obama's pledge "to free the world from the menace of a nuclear nightmare."

Taken as a package, Obama said, his agenda in Europe should be the common goals among people of faith during holy days of Easter and Passover.

"These are two very different holidays with their own very different traditions. But it seems fitting that we mark them both during the same week," Obama said. "For in a larger sense, they are both moments of reflection and renewal. They are both occasions to think more deeply about the obligations we have to ourselves and the obligations we have to one another, no matter who we are, where we come from, or what faith we practice."