Donald Trump's first major foreign policy address marked a victory for his adviser Paul Manafort in the internal war that has consumed the Republican front-runner's campaign.

Mr Manafort, who was brought on board recently to professionalise Mr Trump's approach, has been tussling with the candidate's long-time manager Corey Lewandowski who presided over a free-wheeling, spontaneous operation.

While Mr Lewandoski introduced the campaign motto "Let Trump be Trump," Mr Manafort has sought to make the candidate more "presidential," urging him to hire speechwriters and use teleprompters rather than ad-libbing off hand-scrawled notes.

Mr Manafort has recentlty been touring Washington think tanks, meeting members of Congress, and trying to recruit experts to bulk up the campaign's policy-making staff.

That included consulting the Heritage Foundation, a policy think tank that was a key player in the presidency of Ronald Reagan.

Mr Trump's speech on Wednesday was the first in what is expected to be a series of detailed addresses as Mr Manafort aims to convince establishment Republicans that the billionaire is "Oval Office ready".

It had mixed results with some senior Republican figures praising Mr Trump, and others accusing him of contradicting himself, being overly simplistic, and failing to to give specifics, particularly on how he would eradicate Islamic State of Iraq and the Levant.