Image: Fox News/YouTube screenshot by Chris Matyszczyk/CNET

Republican presidential candidate Donald Trump's says he'll force Apple to bring its manufacturing back to the US and slap a massive tariff on imports.

In his latest speech, Trump said when he becomes president, he's going to make America "greater than ever before". His vision for delivering that goal consists of more military spending, giant walls to keep illegal immigrants out, and a tax regime that will make it impossible for companies such as Apple to refuse his demands to bring manufacturing back to US soil.

"We're going to get Apple to build their damn computers and things in this country instead of in other countries," Trump said in a speech on Monday at Liberty University in Virginia.

His comments about Apple were made at the close of a 50-minute speech, and he didn't elaborate on how Apple could be convinced to bring manufacturing back from China where it builds the iPhone.

However, Trump has similar plans for carmaker Ford, which he once again censured for investing $2.5bn on manufacturing plants in Mexico. His answer to forcing the auto-maker's hand on the issue is a new tariff on vehicles made in Mexico, although the plants he referred to in fact make parts, rather than entire vehicles.

"For every car, truck and whatever else you're building, you're going to pay a 35 percent tax every time you bring a car across the border," he said.

Despite the proposed tariff, the Republican frontrunner insisted he is a "free trader", a term he used earlier this month after mooting a 45 percent tariff on Chinese goods coming into the US.

The only complete product Apple currently manufacturers in the US is the Mac Pro. According to Apple's new jobs creation website, 31 of 50 states provide "parts, materials, or equipment" to make Apple products, while it spent $3bn last year with US suppliers. Apple also claims it was responsible for creating 1.9 million US jobs, while its spending and investment supports 361,000 jobs.

Still, that leaves the nearly one million plant workers in China who build Apple's iPhones at Apple's contractors such as Foxconn.

So what would happen if Trump became president and forced Apple to bring those jobs back to the US?

Unless Trump is willing to let down the great walls he envisions, Apple probably would be stuck with a lot of unmanned machinery.

In a 60 Minutes interview in December, Apple CEO Tim Cook said Apple built its iPhones in China not because hiring was cheaper but rather because it had "vocational skills", such as the tool and die makers it needs to make the iPhone, on a scale that the US currently lacks.

"You could take every tool and die maker in the United States and probably put them in the room we're sitting. In China you would need football fields. It was a focus of their education system and so that is the reality," Cook said.

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