Nice attack: Donald Trump declares 'this is war'

Donald Trump will ask US Congress for a declaration of war against ISIS if he wins November’s presidential election.

The presumptive Republican White House nominee spoke out early today following the Bastille Day massacre in Nice.

"This is war," he said, demanding a tougher crackdown on suspected terrorists.

"Well, it sounds like here we go again," he continued in a TV interview. "It's going to be a whole different world. We're living in a whole different world.

"There is no respect for law and order. There is no respect for anything or anybody. And this has to be dealt with very harshly."

The outspoken property mogul used the terror crisis in France to double down on his controversial stand on immigration in the United States.

Pressed on what he'd do to prevent any further attacks, Trump vowed to make it "very, very hard for people to come into our country" from what he termed "terrorist areas."

"I would be so extreme in terms of documentation," said Trump. "Obama is allowing a lot of people to come in. We have no idea who they are.

"They're from Syria, maybe, but they have no paperwork many times. they don't have proper documentation.

"I would not allow people to come in from terrorist nations.I would do extreme vetting. I would call it 'extreme vetting,' too."

When Fox News TV anchor Greta Van Susteren pointed out that terrorist attacks aren't solely initiated by overseas agents, and that homegrown terrorists were also a problem - referring to the gun massacre at an Orlando, Florida, gay club last month by a US Army veteran - Trump pushed back and said that "second generation" immigrants were also "very bad."

"Second generation turns out to be very bad for whatever reason," he added. "But second generation and again, who knows the new one in France? Maybe it's not, but you probably have a pretty good gut instinct."

Trump had planned to name his running mate, Indiana Governor Mike Pence, at a press conference this morning (Fri), but the unveiling was postponed as the seriousness of the Nice truck attack became clear.

In a separate interview with CNN last night, Democrat presidential nominee Hillary Clinton said she was ‘sick at heart’ over the ‘horrific’ killing spree, which left over 80 people dead.