Fears Republican presidential nominee Donald Trump may be pursuing a Russian agenda with his candidacy have triggered a wave of alarm in the US.

A series of links between Mr Trump's circle of advisers, his policy positions on the future of NATO, his statements of admiration for Russian president Vladimir Putin and even the overlap between his supporters and those touting pro-Russia views online have contributed to this view.

The concerns have prompted a series of high-profile American commentators and analysts to suggest Mr Trump may be getting backing from Russia for his US campaign.

Respected publications such as Slate, economist Paul Krugman writing in The New York Times, and The Washington Post have commented on the convergence between Mr Trump's statements and geopolitical positions that Russia has long sought, with worrying implications should Trump become president.