Trump's threat against Russia runs parallel to a Senate-led effort to pass crippling sanctions on countries that buy Russian energy.

Trump also revealed that Putin had recently offered to assist in mediating between Israel and Iran during their brief June conflict — an offer he declined. “I said, ‘No, no, you help me get a settlement with you, with Russia,’” Trump recounted. “And I think we're going to be doing that too.”

A former Russian prime minister has said Vladimir Putin may be forced to agree a peace deal to end the war with Ukraine by the end of the year. Mikhail Kasyanov said Russia’s “contracting” economy meant the country’s president may have no option but to seek a settlement to stop the hostilities.