US President Donald Trump on Saturday used the Salute to America celebration marking the United States' 250th Independence Day to project confidence in America's future, declaring the country "stronger, richer and prouder than ever before," while mixing patriotic tributes with attacks on communism, praise for the Constitution and assertions of renewed US global dominance.Addressing thousands gathered on the National Mall after weather-related disruptions, Trump said the country remained a beacon for the world and would continue to lead globally."US is stronger, richer and prouder than ever before today.""US has been the hope, light and glory of the world for 250 years; we will always be this or even better."He described the anniversary celebration as a once-in-a-generation moment before unveiling what he said was America's flag from 1776."This is an evening for the ages, this is bigger, a bit boring but beautiful."Key highlights from Trump's speechAmerica will remain the world's leading powerTrump said the US would continue to dominate on the global stage and never lose its standing."We will always be on top, and never let our country fall."He also argued that America's standing in the world had improved under his leadership. "People respect and love our country again, so it is very difficult to get into the US military."Constitution and Second Amendment at the heart of AmericaTrump praised the US Constitution as the foundation of the nation's success over the past 250 years."Constitution of the US is what makes us the finest people on the planet after 250 years."He reiterated his longstanding support for gun rights."We guard your second amendment very very strongly."While speaking about the country's legal principles, Trump also briefly referred to his own legal troubles."Equal justice is promised for all, although I wasn't treated at par, but we won't get into that."Sharp attack on communismTrump devoted a section of his speech to criticising communist ideology, describing it as fundamentally incompatible with American values."We don't want communists in our country.""The communist system is the opposite of the American system and it has never worked."He added that communist ideology should be confronted before it spreads."We'd like to stop the threat before it begins, it's like cancer."Claims of renewed US leadership in spaceTrump also highlighted what he described as America's resurgence in the global space race."We were losing to China and Russia in the space race, now we're way ahead of them."The address formed the centrepiece of nationwide celebrations marking the 250th anniversary of the signing of the Declaration of Independence, with military flyovers, patriotic displays and fireworks commemorating the historic milestone.