The US stands firmly behind the key Nato article invoking unconditional solidarity if any member of the alliance is attacked, President Donald Trump proclaimed to the applause of a large crowd in Warsaw on July 6, before travelling to Germany for possibly tense talks with European partners and Russian President Vladimir Putin.

In a 40-minute speech on the capital’s central Krasinskich Square – his first in Europe since being elected last November – Trump hit all the right notes for a crowd of some 15,000 people eager for an affirmation of Poland’s painful past, the challenges of its present day, and its hopeful future.

“A strong Poland is a blessing to the nations of Europe, and they know that. A strong Europe is a blessing to the West and to the world,” said Trump, going as far as to hail Poland as the “soul of Europe”.

The US leader arrived for a 16-hour stay in the former Eastern Bloc country ahead of the G20 summit meeting in Hamburg on July 7. In Warsaw he met a sympathetic President Andrzej Duda and cheering crowds that were reportedly bussed in from across Poland by the ruling Law and Justice (PiS) party.

Trump’s brief visit lived up to the expectations of the Polish government, which also received a promise of a gas supply deal so that it cannot be held “hostage” by any single supplier.

In his speech, Trump made sure he touched on some key current themes, including the West’s tense relations with Russia. While mindful not to overly antagonise Moscow ahead of his meeting with Putin the next day, he took a measured swing at Poland’s neighbour before moving quickly on to mutual concerns about extremism and terrorism.

“We urge Russia to cease its destabilising activities in Ukraine and elsewhere, and its support for hostile regimes — including Syria and Iran — and to instead join the community of responsible nations in our fight against common enemies and in defence of civilisation itself,” he said.

Earlier in the day he had hinted that Moscow’s leverage over Poland and other countries from the region in terms of gas supplies could end with LNG deals with the US companies, which, Trump said, will never “use energy to coerce your nations, and we cannot allow others to do so”.

Trump and Duda both said new deals – or even a long-term contract – for gas supplies from the US will be signed before long. Poland received the first cargo of LNG from the US company Cheniere Energy in June. The country is hoping to become a gas hub for Eastern Europe, which it plans to bring together under the Three Seas Initiative, a regional undertaking of 12 East European countries to bolster trade and infrastructure investment. The leaders of the 12 states were in Warsaw on July 6 for a Three Seas Initiative summit, which Trump also attended.

Also playing to the sentiment of the Polish administration, Trump said borders must remain closed to “terrorism and extremism of any kind”. Poland’s government is at odds with the European Union – which Trump did not mention at all – over taking in refugees from Muslim countries. Warsaw claims that accepting refugees equals inviting radicals and puts citizens’ safety at risk from terror attacks.

Speaking from behind a bullet-proof glass screen by the monument to the Warsaw Uprising of 1944, Trump painted a picture of the West at war with extremist forces. He hinted, however, that the US will remain a reliable ally standing “firmly behind Article 5 [of Nato], the mutual defence commitment”, while underscoring that European members of the alliance must pay their way as Poland was doing.

That came as a relief for some observers after Trump earlier in the day said he and Duda did not discuss security guarantees regarding the future of around 5,000 US troops currently deployed in Poland. Yet he stressed to the crowd that “these soldiers are not only brave defenders of freedom, but also symbols of America’s commitment to your security and your place in a strong and democratic Europe”.

Trump’s speech was steeped in references to Poland’s difficult history and also celebrated figures, with Copernicus, Chopin, and Pope John Paul II mentioned to waves of applause. In a passage that befitted the monumental location, Trump also spoke at length about the horrors of the 1944 uprising and the tenacity of the participants.

Only when he praised Lech Walesa, the legendary leader of the Solidarity movement that brought down communism who was sitting among opposition politicians for the speech, was booing heard from the largely partisan crowd.

But the banners and placards displayed also reflected a disparate set of concerns and agendas. One large banner strung on a balcony on an approach road to the square bore Ronald Reagan's words that “Poland is not East or West, Poland is at the centre of European civilization”. Another asked “But you won’t sell us to Russia, right?”, and close by an incongruous large sign exhorted “Trump make Bitcoin great!”

Many people in attendance expressed approval for what they’d heard from the US leader.

“This was the speech we were waiting for,” said Maria Knapik, a 22-year-old international relations student from the southeastern Polish city of Rzeszow. “People in Poland are waiting to hear we have allies in the world, even if they are far away. Not allies against anyone in particular though – we shouldn’t be so worried about Russia, that’s all rather a political rather than military matter,” she said.

Some came in the firm conviction that Trump is the right man for the times: “November 9 [Trump’s election victory day] was one of the best moments of my life. He was so badly needed for people who believe in liberty,” said translator Piotr Kalinski, 40, a Warsaw resident.

Others were less enthusiastic. “It was horrible being surrounded by Poles shouting ‘Donald Trump’,” said Zeve Sandersen, 25, a tourist from New York who was visiting Warsaw on his way to Germany and had no idea the US president would be appearing. “I'll hear Trump 340 days a year and here he is on my 20-day vacation!”