President Obama concluded his four-nation European trip Saturday after achieving much, if not all, of what he intended to. He did so by using, more than anything else, the original tool of his public diplomacy — himself and his story.

He had not made a multi-stop trip to Europe since his first year in office, and his goal, in large part, was to show Europeans that his outreach to Asia and other regions since taking office has not come at the expense of the country’s oldest alliance.

“I wanted to make sure that everybody in our country, but everybody around the world, understands that the transatlantic alliance remains a cornerstone, a foundation stone, for American security,” Obama said Saturday at a news conference in the Polish capital.

But Obama did so without announcing significant new policy. Instead, his biography often substituted for — or served to represent — his policy.

In Ireland, he drank a beer with the residents of Moneygall, birthplace of his maternal great-great-great-grandfather, and electrified a downtown audience in Dublin in need of cheering up after years of recession.

In Britain, Obama and the first lady, Michelle, lodged at Buckingham Palace and, at the nine-century-old Westminster Hall, he presented himself to Parliament as “the grandson of a Kenyan who served as a cook in the British army.” The audience erupted in applause.

And here in Poland he acknowledged that he shares its heritage, if only through cultural osmosis.

“I am part of Poland because I come from Chicago,” he said. “And if you live in Chicago and you haven’t become a little bit Polish, then something’s wrong with you.”

Obama’s project to remake the U.S. image abroad has always relied, at its core, on his own against-the-odds story. And the adoring reception he received, from the public and its elected leaders, suggested the message still resonates here.

His achievement, though, is difficult to measure. How his public diplomacy will translate into policy that strengthens his hand in Afghanistan, Libya and the broader Middle East remains unclear.

But at the G-8 summit in Deauville, France, Obama did reap the benefits of his effort to “reset” relations with Russia, securing from Russian President Dmitry Medvedev a pledge to help push Libyan leader Moammar Gaddafi from office.

Russia had previously spoken critically about the NATO-led mission, saying it is exceeding its U.N. mandate. Whether Gaddafi accepts Russian mediation is another matter, but Medvedev’s position leaves the Libyan leader more isolated than ever.

Obama warned here Saturday that political change in North Africa and the Middle East would be a difficult, halting process, but he argued that U.S. support for the democratic transition underway is essential to ensure its success.

In making his case, Obama drew on lessons he said he learned during his trip — from Ireland, where a 1998 peace agreement in Northern Ireland ended decades of sectarian strife, and from Poland, where Solidarity challenged Soviet communism years before its fall.

“It’s not enough just to have the energy, the initial thrust of those young people in Tahrir Square, or the initial enthusiasm of the Solidarity movement,” Obama said.

Even at a time of fiscal difficulty at home, he said, “I want the American people to understand we’ve got to leave room for us to continue our tradition of providing leadership when it comes to freedom, democracy, human rights.”

But Obama’s success in rallying specific support around the Arab Spring, as the uprisings across North Africa and the Middle East are known, was more qualified.

The world’s wealthiest countries concluded their summit without a specific pledge of aid to Egypt and Tunisia, now in the midst of a rocky transition to democracy.

The group said $20 billion may be available to the two countries for “suitable reform” projects, and French President Nicolas Sarkozy said he hoped several Arab countries and the International Monetary Fund would also chip in with loans.

In assessing the result, Mike Froman, the deputy national security adviser for international economic affairs, said, “More important than any numerical figure, I think, is the vision it lays out.”

Obama’s stop here provided an opportunity to assure Central and Eastern European leaders that he cared as much about their interests as he does about Russia’s.

Those sentiments derived from his first year in office, when he announced a redesign of the Bush-era missile defense system that would no longer require Poland to host 10 land-based interceptors.

Polish leaders and others in the region saw the move as a concession to Russia, which, as Medvedev made clear in Deauville, still views the plan as a threat to its intercontinental ballistic missiles and the overall “strategic balance.”

Poland also remains concerned about Russia’s sometimes-aggressive posture in the region. Russia has cut gas shipments to Europe in recent years to protect its policy interests, and invaded Georgia in 2008 over the status of a breakaway region both countries claim.

Prime Minister Donald Tusk said Poland’s security was the first topic he discussed with Obama, and he said the president assured him that, as a NATO member, Poland would be protected.

“He said that NATO exists to defend NATO,” Tusk said at their joint news conference.

Obama also agreed to send a contingent of U.S. F-16s and C-130s to train alongside Poland’s air force, a largely symbolic gesture of support for its security.

Obama’s approach here was based less on specific policy pledges than on a public show of respect — from his extended visit to the Warsaw Ghetto memorial to the announcement that he would push Congress to ease visa requirements for Polish travelers to the United States.

In a meeting Saturday with founders of Solidarity, Obama told the group, which had just returned from Tunisia, that “your action inspired a cause of freedom.”

“One of the important roles that Poland can play is not just as a promoter of ideas but as a living example of what is possible when countries take reform seriously,” he said at the news conference.

Tusk said the two discussed energy security, expanding commercial ties, the crackdown on civil society in Belarus, and the military project in Afghanistan, where Poland has 2,600 troops.

But Tusk, who said he researched Ralph Waldo Emerson — among Obama’s “favorite thinkers” — in preparation for the visit, also picked up on the president’s overall message to Europe.

“We believe in Poland that you are one of us,” he said.