Donald Trump has opened up his campaign to win back the US presidency by railing against the “dark forces” which he says are lined up against him.

At the airfield rally in Waco, Texas, in front of thousands of supporters, the former US president called the New York City investigation into hush-money payments an expletive.

The campaign event marked Trump’s return to a traditionally conservative state, in which he remains very popular.

However, his decision to hold the rally in Waco - best known for an armed standoff 30 years ago - has also raised eyebrows.