US President Donald Trump has pledged to protect the American gun owners' right to keep and bear arms, assuring them that they now have a “true friend” in the White House.

Speaking at the National Rifle Association (NRA) in Atlanta on Friday, Trump said that his election marked the “crashing end” of an “eight-year assault” on gun ownership by the administration of his predecessor Barack Obama.

“No longer will federal agencies be coming after law-abiding gun owners. No longer will the government be trying to undermine your rights and freedoms as Americans,” Trump told America’s most powerful gun lobby, which supported him during last year’s campaign run.

“You have a true friend and champion in the White House,” he said. “No longer will federal agencies come after law abiding gun owners.”

Trump was the first sitting US president to attend the annual NRA meeting in 34 years, after a similar visit by former President Ronald Reagan in 1983.

In early March, the NRA hailed Trump’s approval of a bill that removes Obama-era legal restrictions for 750,000 people with severe mental illness to purchase firearms.

After reaffirming his commitment to protecting the Second Amendment, the new Republican president used the speech on the eve of his 100th day in office as an opportunity to demonstrate his dedication to the principles he laid out as a candidate.

Some of Trump’s supporters have been disappointed by his U-turns on a range of issues such as China and the NATO.

Most recently, Trump postponed his plans for building a wall on the border with Mexico to stem a feud with Democrats that risked a government shutdown. He tried to do some damage control on Friday.

“You need the wall to stop the human trafficking, to stop the drugs, to stop the people,” he told the annual NRA gathering.  “We need the wall. We are going to get that wall.”

The NRA said Thursday that they made the right choice by endorsing Trump.

“He ran as one of the most unabashed pro-second amendment candidates in my lifetime, and he really has kept his promises and done a lot for people who care about the Second Amendment and the Constitution in his first 100 days,” said Jennifer Baker, an NRA spokeswoman.