The president delivered his remarks at the site of a Warsaw monument to the 1944 Polish resistance against German occupation, a symbol of the country's struggle to shake the brutal Nazi invasion during World War II. He cast Poland as an example of a nation that had persevered despite grave challenges, saying it offered "the story of a people who have never lost hope, who have never been broken, and who have never forgotten who they are."
Trump's address in front of a friendly crowd came ahead of his travels to Germany for the Group of 20 Summit of world leaders in Hamburg, where he will meet with several European leaders who view him sceptically and hold starkly different views on globalization.
Shortly after arriving in Germany, Trump held a private meeting with German Chancellor Angela Merkel, with whom Trump has had a chilly relationship during his first months in office. Appearing briefly before the media, the pair appeared casual with another and chatted freely. They shook hands while looking directly at each other.
Merkel tried to play down tensions with Trump ahead of the G-20 meeting.
"There are just differing ideas of globalization, and let's see what we can get done together," she told reporters shortly before she met Trump at her Hamburg hotel, the grand Atlantic Kempinski. "I think that globalization can be organised in a way that it's a win-win situation. It doesn't always have to be the case that there are winners and there are losers."
Merkel said that negotiators were still hammering out an agreement on climate, one of the areas of sharpest disagreement between the Trump administration and the rest of the leaders of the summit.
Earlier in the day in Poland, Trump's praise of that nation's defence spending underscored his disdain for Germany's more modest expenditures. Poland's right-wing government has been in conflict with Merkel and many other leaders in the European Union, who have criticized its crackdown on press freedoms and erosion of democracy since leaders came to power in 2015.
Trump, however, offered no mention of Polish democracy concerns, unlike President Barack Obama's visit to Warsaw for a Nato summit almost exactly a year ago. Trump joined with Polish President Andrzej Duda in hammering the media.
While in Germany, Trump is also expected to meet with Russian President Vladimir Putin in their first face-to-face encounter since Trump's inauguration. During his address in Warsaw, Trump rebuked Russia on several counts, including its military incursion into Ukraine.
"We urge Russia to cease its destabilising activities in the Ukraine and elsewhere and its support for hostile regimes, including Syria and Iran, and instead join the community of responsible nations in our fight against common enemies and defence of civilisation itself," Trump said.
Earlier in the day, Trump refused to say definitively that he believes Russia was solely responsible for interference in the 2016 U.S. election. "I think it could very well have been Russia, but I think it could well have been other countries. I won't be specific," Trump said at a news conference in Warsaw with Duda. "I think a lot of people interfere. I think it's been happening for a long time."
Trump's speech here was also notable for its explicit commitment to Article 5, the collective security provision of the Nato treaty: "The United States has demonstrated not merely with words, but with its actions, that we stand firmly behind Article 5, the mutual defence commitment," Trump said.
Trump had notably left out a mention of Article 5 during a speech in late May at Nato's new headquarters in Brussels. Every U.S. president since Harry Truman in 1949 has pledged to honor the policy that an attack on an alliance nation is an attack on all of them. The provision has been invoked once, after the Sept. 11, 2001, terrorist attacks in the United States.
The stop in Poland was a highly symbolic one for the new American president. The Eastern European nation is a critical U.S. ally and strategically important state in Europe. Poland is one of the few Nato countries to have honoured an agreement to contribute at least 2 percent of their gross domestic product to their own defence, an issue that Trump has repeatedly raised during his campaign and since taking office.
But Trump said that military spending alone is not enough to preserve Western civilisation.
"We can have the largest economies and the most lethal weapons of anywhere on Earth, but if we do not have strong families and strong values, then we will be weak and we will not survive," Trump said. "If anyone forgets the critical importance of these things, let them come to one country that never has. Let them come to Poland, and let them come here to Warsaw and learn the story of the Warsaw Uprising."
Poland's right-leaning populist nationalist government is a natural ally for Trump. The country's Law and Justice Party has embraced some of the main pillars of Trump's candidacy, including a similar resistance to accepting Muslim refugees into their country.
"While we will always welcome new citizens who share our values and love our people, our borders will always be closed to terrorism and extremism," Trump said. "We cannot accept those who reject our values and who use hatred to justify violence against the innocent."
At the news conference earlier in the day, Trump praised Poland for aiding in the fight against the Islamic State. And in his public remarks, he suggested that the two nations' shared position on refugees was not aimed at closing their respective borders but rather was an effort to protect their nations from extremism.
"We must stand united against these shared enemies to strip them of their territory, their funding, their networks, and any form of ideological support," Trump said.
Central and eastern European nations, which are particularly concerned about the threat of growing Russian influence in the region, view Trump's presence here as a reassuring sign that the United States remains committed to the security of the region.
"We must work together to counter forces, whether they come from inside or out, from the South or the East, that threaten over time to undermine these values and to erase the bonds of culture, faith and tradition that make us who we are," Trump said.