Warsaw, Poland CNN  — 

President Barack Obama departed here Saturday confronting again the frustrating sting of his unfinished business.

The lingering shortfalls of his presidency – on guns, race, war, and politics – seemed to confront Obama in each hallway and beyond every podium during his two-day stop in the Polish capital.

Obama insisted Saturday he’s not keen to assess his own legacy as his term winds down, preferring to leave that task to historians. He says he’s focused more on finishing his presidency at a sprint. And for the first time in years, a majority of Americans say in polls they approve of his job performance.

That doesn’t mean, however, that tough realities about what he has and hasn’t accomplished aren’t rapidly settling in.

In Warsaw, his three appearances decrying gun violence in America joined a seemingly endless stream of statements following mass shootings. His press secretary said Friday that inability to convince Congress to pass gun control was the President’s biggest frustration.

The racial undertones of the violence placed Obama, yet again, in the fraught position of calling attention to persistent racial disparities, which he says he’s experienced himself, while also championing the police many minorities mistrust.

On Sunday, the President condemned citizens who attack police officers, saying they are performing a “disservice to the cause” of criminal justice reform.

“Whenever those of us who are concerned about fairness in the criminal justice system attack police officers, you are doing a disservice to the cause,” Obama said at the Moncola Palace in Madrid.

He’s sought to balance those sentiments before, after police brutality in Baltimore, riots in Ferguson, and the arrest of a black Harvard professor at his own home. Despite those efforts, a Pew poll showed this week a majority of Americans feel he hasn’t made progress on race relations.

Obama responded Saturday that change takes time.

“If my voice has been true and positive, then my hope would be that it may not fix everything right away, but it surfaces problems, it frames them; it allows us to wrestle with these issues and try to come up with practical solutions,” Obama said during a press conference at the end of a NATO summit here.

“That’s not going to happen right away, and that’s okay,” he continued. “We plant seeds, and somebody else maybe sits under the shade of the tree that we planted.”

Even as Obama was focused on violence at home, the European leaders gathered in Warsaw this week were desperate for their own reassurance from the U.S. leader.

On what was likely to be his final presidential visit to the continent, Obama found Europe at its most fragile state in decades – even after he made a vocal, lengthy call for unity two months ago.

Obama has sought to downplay the ramifications of the Brexit vote, though the security and economic consequences remain largely unknown. Obama urged leaders to execute a responsible divorce between Britain and the EU during talks in Poland.

But the air of disappointment was palpable as the leaders face an uncertain future.

“In public debates in Washington, London, Berlin, Paris, and Warsaw, we hear anti-democratic slogans more and more, calling for national egoism, isolationism,” said Donald Tusk, the president of the European Council. “Whoever undermines the foundations of liberal democracy harms one and the other.”

Even conversations with his friend David Cameron this week were tinged with letdown. The outgoing British prime minister is arguably Obama’s closest partner on the world stage (aside from the stalwart German chancellor Angela Merkel). But this week Cameron was swathed in a disappointing aura of failure.

The images of the pair smiling broadly as they both completed their final NATO summit masked what other leaders described as a growing sense of unease among the Western ranks about Britain’s pending exit from the EU.

“There is almost no other subject on the table when I get together with my colleagues,” British foreign secretary Philip Hammond told reporters in Poland.

It’s not as if leaders didn’t have much else to discuss. NATO, which in recent years faced an identity crisis, has found something of return to form in its attempts to counter Russian aggression on its “eastern flank” (a decidedly NATO phrase that leaders seemed eager to use in demonstration of a certain borderless solidarity).

A decision to deploy four battalions to Eastern Europe – including a U.S.-led force in Poland – went largely unnoticed in the United States. Administration officials, which in the past downplayed comparisons to Soviet-era tensions, seemed more eager to note the parallels in Poland.

“Four battalions – that represents the largest movement of NATO personnel since the end of the Cold War,” Elissa Slotkin, the acting Assistant Secretary of Defense for International Security Affairs, told reporters in Warsaw.

For Obama, that’s not necessarily a win. As a president who entered office eager to deescalate conflicts, and to normalize relationships around the globe, deploying American troops to counter Russia has been a necessity rather than an eager muscle flex.

And the fact that NATO leaders are still devising ways to force Russian President Vladimir Putin to reverse course more than two years after he annexed Crimea speaks to a frustratingly slow process.

Incremental progress has become a hallmark of Obama’s governing mantra. Stymied by Congress on issues like gun control, immigration, and climate change, Obama has pointed to an inch-by-inch approach he says will pay off down the road.

That payoff will largely depend on Obama’s successor, a main reason he’s expected to campaign heavily for the presumptive Democratic presidential nominee Hillary Clinton. But even the President’s much-anticipated campaign trail debut with Clinton last week was marred when the FBI director declared she’d been “extremely careless” with secret information a few hours before their rally.

When Obama announced the next day he was slowing the withdrawal of troops from Afghanistan, it was another reminder that the change he promised coming into office has happened at a sometimes-frustratingly slow pace.

“As Commander-in-Chief of the most powerful military in the world, I spend a lot of time brooding over these issues,” Obama said Saturday when asked about the conflicts from which he’s been unable to full withdraw U.S. troops. “And I’m not satisfied that we’ve got it perfect yet. I can say honestly, it’s better than it was when I came into office.”