Donald Trump claimed Wednesday that Iran is planning a "sneak attack" against US forces in Iraq, without providing any evidence or sourcing for the assertion.

"Upon information and belief, Iran or its proxies are planning a sneak attack on U.S. troops and/or assets in Iraq. If this happens, Iran will pay a very heavy price, indeed!" he wrote on Twitter.

Tensions between Iran and the US have been sky-high since the US assassination of Iranian general Qassem Soleimani in January. Since then, US bases in Iraq have come under attack a number of times.