Donald Trump

"People start thinking behavior that in normal times we would consider completely unacceptable and outrageous becomes normalized," Obama said during a news conference at the tail end of his visit to Laos.

"People start thinking that we should be grading on a curve," he said. "But I can tell you from the interactions I have had over the last eight or nine days with foreign leaders that this is serious business."

But he added that a "court system" should be set up in the military to better deal with what he called "a massive problem."

"26,000 unreported sexual assaults in the military-only 238 convictions. What did these geniuses expect when they put men & women together?" Trump had tweeted in 2013.

When asked about the tweet by moderator Matt Lauer, Trump didn't back down.

Trump calls for military spending increase

Mr Trump called for more troops, more planes and more boats at a rally in Philadelphia.

He also wants US generals to come up with a plan to defeat the self-styled Islamic State (IS) in his first 30 days in the White House.

Recent polls show the race for the presidency has narrowed.

Democrats and even some Republicans have painted Mr Trump as unfit to serve as US commander-in-chief but he has made up some ground on rival Hillary Clinton.

So began the homestretch to Election Day, as both candidates on Tuesday put national security squarely at the center of the 2016 campaign in the belief that it gives them the advantage.

Trump began by unveiling a list of 88 retired military leaders endorsing his candidacy, including four four-star generals and 14 three-star flag officers.

Then, alongside retired Lt. Gen. Michael Flynn at an event in Virginia Beach -- where fighter jets could be heard whooshing overhead -- Trump said of Clinton that "virtually every decision she's made has been a loser."

Zeid Ra'ad Al Hussein, UN high commissioner for human rights, directed a brutal verbal assault on controversial Dutch lawmaker and leader of the Dutch Freedom Party (PVV), Geert Wilders, criticizing him and others for spreading hatred and prejudice for the sake of political points.

"I wish to address this short statement to Mr. Geert Wilders, his acolytes, indeed to all those like him -- the populists, demagogues and political fantasists," said Hussein, addressing a security conference Monday at the Hague.

Recognizable rhetoric?

The group of retired generals and admirals declared the Republican nominee "has the temperament to be commander-in-chief".

Mr Trump, who has highlighted veterans' issues during his campaign, called their support "a great honour".

He has meanwhile been dismissing claims of impropriety over a political donation to a Florida official.

The Washington Post reported on Monday that in 2013 Florida Attorney General Pam Bondi had been considering fraud charges against Trump University.

"Every time I think about Trump I get allergic," said the Democratic nominee in the midst of her coughing outbreak during a Cleveland rally, Ohio. Behind Clinton, running mate Tim Kaine clapped while the audience laughed in response.

Kellyanne Conway, Trump's campaign manager, seized on the episode to tweak Clinton over her distance from the media -- including not holding a full-blown press conference since last December.

"Must be allergic to media. Finally spent a minute w/ them," Conway wrote on Twitter.

Trump spoke to members of the Great Faith Ministries, a nondenominational church in Detroit, part of his outreach to what is typically a sizable Democratic voting bloc. His visit, however, was greeted by protests outside of the church ahead of his arrival.

Sitting in a pew at the front of the congregation, Trump took a selfie with a church member and at one point held up a baby over his shoulders. He then addressed the congregation.

He told the congregation he "fully understands that the African American community has suffered discrimination".

Polls say Mr Trump, who is lagging behind Mrs Clinton, has low support among black and Hispanic voters.

He was accompanied by Ben Carson, the former Republican presidential hopeful who grew up in the city.

Marco Gutierrez was explaining why he supports Donald Trump, a day after the presidential candidate's visit to Mexico.

"My culture is a very dominant culture and it's imposing and it's causing problems," he told MSNBC.

"If you don't do something about it, you're going to have taco trucks on every corner."

His warning led to ridicule on social media as people suggested the prediction sounded like a utopian vision of the US.