Donald Trump riled up his supporters in Florida on Friday, saying Iranian ships harassing the US Navy would be 'shot out of the water' under his presidency.

'With Iran, when they circle our beautiful destroyers with their little boats and they make gestures at our people that they shouldn't be allowed to make, they will be shot out of the water,' Trump said.

Last weekend, an Iranian boat came within 100 yards of a US coastal patrol ship in the Persian Gulf, forcing the USS Firebolt to maneuver out of the way in the fourth confrontation in the past month.

Donald Trump riled up his supporters in Pensacola, Florida, on Friday, saying Iranian ships harassing the US Navy would be 'shot out of the water' under his presidency

Republican presidential candidate Donald Trump gives a thumbs up as he speaks during a rally in Pensacola

His incendiary comment, which would most likely launch the country in a war if it was carried out, came after recent confrontations between the US and Iran on international waters

While Trump has tried to soften his tone and stick to teleprompters in the three weeks after his campaign shake-up, Friday's rally showed signs he was reverting to his controversial ways.

His incendiary comment, which would most likely catapult the country in a war if it was carried out, came after a series of recent confrontations between the US and Iran on international waters.

And yet Trump accused Hillary Clinton of being 'trigger-happy' on Friday, calling her an 'unstable person' whose policies 'produced only death, destruction and not diplomacy'.

This week, the Republican presidential nominee laid out a multi-billion dollar plan to bolster the military, which would become 'so strong that nobody's going to mess with us'.

And thousands of supporters applauded his taunts in Florida on Friday, and later cheered 'USA! USA!' in response.

Trump has based his foreign policy beliefs on keeping the United States out of what he called 'endless wars' in the Middle East.

The business tycoon, who has been criticized for his frequent praise of Russian President Vladimir Putin, also mentioned a recent incident in which a Russian fighter jet came within 10 feet of a US Navy surveillance plane over the Black Sea.

'Putin laughs, believe me, he laughs at our leaders. Yesterday he had a plane 10 feet away, taunting us, toying with us, just like Iran,' he said.

The USS Firebolt (file photo from 2011) was forced to change course after an Iranian Navy patrol boat came within 100 yards of it last Sunday despite repeated warnings

The incident came after the USS Nitze fired flares at Iranian patrol boats after the approached at speed and in an 'unsafe and unprofessional' manner, officials said

The confrontations are taking place in a narrow band of international water that runs between Iran on one side and the United Arab Emirates on the other

He also said Hillary could kill someone and get away with it because she avoided prosecution in regards to her use of a private email server.

'Because she's being so protected, she could walk into this arena right now and shoot someone with 20,000 people watching, right smack in the middle of the heart, and she wouldn't be prosecuted,' Trump said.

His comment was reminiscent of his own popularity claims in January, when he told supporters in Iowa: 'I could stand in the middle of 5th Avenue and shoot somebody and I wouldn't lose voters.'