US President Donald Trump has pledged a "massive” increase in military spending, saying he will implement “the greatest military build-up in American history.”

In a wide-ranging speech on Friday at the Conservative Political Action Conference (CPAC) outside Washington, the controversial president vowed to keep his election promises to the American people, including securing the border and fighting terrorism, as well as rebuilding US industry and the country’s military.

Trump said the military buildup is necessary to fight against the Daesh (ISIL) terrorist group and because the US does not “win anymore” in wars.

“We don't win anymore. When was the last time we won? Did we win a war? Did we win anything? Do we win anything?” Trump asked.

“We're also put nothing a massive budget request for our beloved military. We will be substantially upgrading all of our military, all of our military, offensive, defensive, everything, bigger and better and stronger than ever before. And hopefully, we'll never have to use it, but nobody's gonna mess with us,” he added.

“It will be one of the greatest military build-ups in American history. No one will dare question as they have been because we're very depleted, very, very depleted. Sequester. Sequester. Nobody will dare question our military might again. We believe in peace through strength and that's what we will have,” Trump said.

The US president said Washington has “spent trillions of dollars overseas, while allowing our own infrastructure to fall into total disrepair and decay,” a stark contradiction of his previous remarks.

Trump lashed out at his predecessors for spending huge amounts of money on wars in the Middle East.

“If our presidents would have gone to the beach for 15 years the Middle East would have been in better shape”, he said.

U.S. residents in Mexico protest against President Donald Trump's foreign policy towards Mexico outside the U.S. embassy, in Mexico City, February 23, 2017. (Photo by Reuters)

Trump also repeated his election campaign call for building a wall on the US-Mexico border and renewed his harsh criticism of the media, describing the press as "fake news.."

"They (media) are the enemy of the people, because they have no sources. They just make 'em up when there are none," he said..

"I am only against the fake news media or press - fake, fake. They have to leave that word. I'm against the people that make up stories and make up sources. They shouldn't be allowed to use sources unless they use somebody's name," Trump said.

The US president is under fire by news outlets for his controversial policies, particularly his executive orders and his advisors’ alleged contacts with Russia.

Earlier on Friday, Trump criticized the Federal Bureau of Investigation (FBI) for failing to stop leaks of national security information to the media and directed the agency to find those who pass on classified information.

"The FBI is totally unable to stop the national security 'leakers' that have permeated our government for a long time. They can't even find the leakers within the FBI itself. Classified information is being given to media that could have a devastating effect on US FIND NOW," Trump wrote on Twitter.

His remarks came amid media reports saying the FBI rejected a request by the White House to publicly dispute media reports that Trump’s campaign advisers kept regular contacts with Russian intelligence agents during the 2016 presidential election.