Donald Trump alarmed seasoned observers last night with provocative rhetoric about North Korea and Christians in his first State of the Union address, highlighting the plight of a tortured Christian defector who was in the audience.

Trump's speech concluded with a description of Ji Seong Ho's suffering in explicit detail. 'He woke up as a train ran over his limbs. He then endured multiple amputations without anything to dull the pain,' the president said. 'His tormentors wanted to know if he'd met any Christians. He had – and he resolved, after that, to be free.'

Trump linked the story to the country's threat to the West and desire for nuclear weapons. 'North Korea's reckless pursuit of nuclear missiles could very soon threaten our homeland,' he said. 'We need only look at the depraved character of the North Korean regime to understand the nature of the nuclear threat it could pose to America and to our allies.'

Trump also had in the audience the parents and siblings of Otto Warmbier, a Christian American student who was sentenced to 15 years in a North Korean forced-labour camp, and who died after being sent back to the US with severe injuries. 'Tonight we pledge to honour Otto's memory with total American resolve,' Trump said.

Ji, who lost his left hand and foot during North Korea's famine in the mid-1990s, was cheered as he held his crutches aloft. Ji has reportedly argued that Christian believers have a duty to destroy the North Korean regime. According to a 2013 profile of Ji in the Christian Post: 'Despite North Korea's cruel imprisonment and murder of anyone who advocates religion in the country, there is a Christian responsibility to tear down North Korea's wall against Christianity and religion so that North Koreans may begin to worship and find joy, he stressed.'

The New York Times speculated that, 'Ji's presence could signal that Trump is trying to enlist his evangelical base in a crusade'.

Also last night, Trump apparently sought to appease some Christian critics of his plan to rescind the Obama-era programme that protected 'Dreamers' from deportation.

Although he said 'Americans are Dreamers too,' the president added that he would grant around 1.8m Dreamers legal status, including a path to citizenship – but only in exchange for increased enforcement, the construction of his long-promised border wall with Mexico, and a restructuring of legal immigration that prioritises higher-skilled immigrants over reuniting families.

Democrats had invited Dreamers who were due to lose their protection from deportation to be their guests at the event.

Rev Dr Samuel Rodriguez, the president of the National Hispanic Christian Leadership Conference who has sometimes criticised Trump on immigration policy, cautiously welcomed the move and called for bipartisan cooperation. 'There has been far too much finger pointing and "gotcha politics" being played in Washington in recent times. The schoolyard routine of racing to be the first to accuse the other side of wrongdoing, will never solve our problems – only leadership, decency and moral courage can do that,' he said.

'In order to solve the nation's most serious challenges, we all must come together as one people who share one common destiny. We must work together, Democrats and Republicans, Independents and Libertarians, the Green Party and the Tea Party, to care for the both Dreaming child and the unborn; for the addict and the inmate; for the alien on our shores and the native-born forgotten man and woman. We can do it all, but it will require us all.'

Meanwhile, World Relief also welcomed Trump's move but called for a more consistently 'compassionate' approach, saying: 'We are heartened by the president's promise to work with Congress in a bipartisan fashion on multiple initiatives. Likewise, we are convinced that our nation is poised to achieve a permanent legislative solution to protect 1.8 million Dreamers and provide for them a pathway to citizenship. While we celebrate this progress, we also pray this is just the beginning of a more compassionate posture toward immigrants who face various kinds of vulnerability.'

The Christian global aid development organisation also called on Trump to do more to protect Christian refugees from around the world, adding: 'While recent weeks have sparked hope that we are beginning to turn a corner and make progress on a plan to protect Dreamers, we are still eager for the administration to commit to resettling 45,000 refugees this fiscal year and ensure that we remain a more welcoming country for the persecuted. We in particular are concerned about the 60 per cent reduction in the resettlement of Christian refugees who remain in dangerous situations around the world. The United States must continue to be a beacon of hope and freedom for the world's persecuted by being more welcoming of them to our shores.'

It also expressedconcerns about the potential cuts to family-based immigration, saying: 'Our conviction remains unchanged, that immigrants and refugees are an asset, not a liability to America.'

Elsewhere in the speech, Trump also called on Republicans and Democrats to work together on a $1.5 trillion infrastructure proposal, providing few specific details.

'This is our new American moment. There has never been a better time to start living the American Dream,' he said.

A CNN/SSRS snap poll after the State of the Union address found that 48 per cent of those surveyed had a 'very positive' response to the speech and 22 per cent 'somewhat positive'.

But in a post-speech rebuttal, the Massachusetts Representative Joe Kennedy III, the grandson of Robert F Kennedy who some see as a potential Democrat challenger to Trump, branded the President a bully. 'Bullies may land a punch. They might leave a mark,' Kennedy said. 'But they have never, not once, in the history of our United States, managed to match the strength and spirit of a people united in defence of their future.'