US turns 250 as Trump warns of 'attack' on identity

US President Donald Trump lashed out at what he called a fresh threat against the country's identity, taking aim at domestic "radicals and extremists" as the US celebrates the 250th anniversary of its independence.

In a speech dripping with patriotism, Mr Trump lauded American exceptionalism and praised its past leaders, speaking at Mount Rushmore with its giant carved heads of four of his predecessors.

"As we approach this magnificent anniversary, we see our American identity under a renewed attack," he said.

Mr Trump claimed that there was "a resurgence of the communist menace in our land".

It is a theme that he has repeatedly emphasised in recent weeks, as the anti-establishment left of the Democratic Party carried a surge of US primary victories.

The president has cast the rise of the left ahead of November's midterm elections that "communists" are on the rampage, posing a major "threat" to the country.

"In recent years there's been an undeniable attempt to change this exceptional character, to beat the American spirit out of us, alienate us from our history," Mr Trump said.

While his language fell short of the more violent anti-immigrant rhetoric he has regularly wielded in past speeches, the underlying message was clear enough.

"You do not have to be born here, but you do have to love what we have built," he added.

The location of Mr Trump's speech strikes a fitting image for a president who views himself as being one of the greats.

His supporters have even introduced legislation to have his likeness chiselled beside those of George Washington, Thomas Jefferson, Abraham Lincoln and Theodore Roosevelt.

At every stage, the 80-year-old Republican has sought to turn the United States' big anniversary into a celebration of himself.

Later, Mr Trump will hold a campaign-style political rally on the National Mall in Washington, along with flyovers by military jets and what he has billed as the world's biggest fireworks display.

'Really long speech'

However, the US, under Mr Trump's leadership, is deeply divided at what should be a time of national unity.

His approval ratings are near historic lows, fuelled largely by the war in Iran and the skyrocketing cost of living.

His Democratic opponents have castigated him over his immigration policies, family's growing wealth and attempts to expand presidential power.

Mr Trump's attempts to stamp his political brand on America's 250th anniversary have, meanwhile, not always gone to plan.

A Trump-linked organisation called 'Freedom 250' has taken control of many of the festivities from the bipartisan 'America 250' group, leading many people to stay away from key events.

A 'Great American State Fair' in the capital designed as a celebration of the country's birthday has drawn sparse crowds and widespread mockery for its empty booths.

A record-breaking heatwave also kept many visitors away, although Mr Trump declared himself undeterred by the heat.

"On July 4 it's going to be approximately 107 degrees (41C) out, and I'm going to go and I'm going to make a really long speech - just to show that I can do anything," he said earlier this week.

A recent Quinnipiac University Poll showed 61% of Americans thought the US was not living up to the ideals stated in the Declaration of Independence - though opinion on that was divided, with most Republicans thinking it did, and most Democrats thinking it did not.

"The Fourth of July really is a moment of freedom, but I have to be honest, in these political times, it hasn't been as exciting to me," a 49-year-old special education teacher, said in Los Angeles.