Trump threatens to ‘annihilate’ Iran if it fails to make deal

President Donald Trump will vow at the UN General Assembly Tuesday to use "unmatched" US military power to secure Washington's interests in Latin America, according to extracts of his speech released by the White House.

"The United States will no longer permit threats to America to gain a foothold anywhere in the Western Hemisphere. And if necessary, we will use our unmatched military might to secure the vital national interests of the United States," Trump was to say.

The Republican leader will also accuse Cuba - which has been in Washington's sights since the US military operation to topple Venezuela's Nicolas Maduro in January - of having "cultivated ties" with left-wing groups in the United States.

The US president is set to meet interim Venezuelan leader Delcy Rodriguez on the sidelines of the UN later Tuesday.

Trump also told the United Nations General Assembly that he had to choose whether to "annihilate" Iran if it fails to make a deal to end the Middle East war.

"I have a big decision to make - will a deal be made with Iran that lets them rebuild and create a far greater country than it ever was before, maybe one of the greatest in the Middle East or even the world?" Trump said.

"Or do I annihilate the Islamic Republic and do it quickly, never giving them a chance to kill and destroy people and countries again? Do I drive them into hell with no chance of survival and no hope of future greatness or generations?"

But Trump reiterated that he thought an agreement was possible before US midterm elections in November - in which his Republican party faces losing control of Congress at least partly due to high fuel prices caused by the war.

"I believe we'll make a deal right after the election because it doesn't make sense for them not to," Trump said.

"They're waiting to see how I do in the midterm election. What they don't realize is that I'm not running. I did that already, and won in a landslide."