"No, I didn't undercut anybody", Trump said.
As for Tillerson's reported "moron" comment, the president said, "I think it's fake news".
Tension has been simmering between the pair for some time over North Korea, with Trump's aggressive rhetoric at odds with Tillerson's more measured approach. The Twitter rebuke revived rumours that Tillerson is unhappy at hs post, but he insists he has no intention of resigning.
Huge energy potential in open ocean wind farms: research
The energy that turbines tap into starts as faster winds at higher altitudes, which are brought down towards the surface. But extracting efficient energy from wind involves more than putting turbines in the path of gale-force winds.
The spat came up as Trump addressed reporters before a meeting with Henry Kissinger, secretary of state to two former presidents, this morning at the White House. "I think I'm actually strengthening authority".
After being shown an image charting the steadily falling size of the US nuclear arsenal since the height of the Cold War during a meeting with top national security officials in July, President Donald Trump reportedly expressed support for a tenfold expansion of America's stockpile of nukes-a move critics said would spark a "global arms race" and dramatically increase the threat of a nuclear catastrophe. He also said he still has confidence in Tillerson as secretary of state. "And I can tell you who is going to win".
Trump said Tillerson "never threatened to resign" and the news network would have known that if it had spoken to him about the matter before publishing its report.
Shortly after winning the election, Trump tweeted that America "must greatly strengthen and expand its nuclear capability until such time as the world comes to its senses regarding nukes". Trump claimed in one of his tweets.
"The president certainly never implied that the secretary of state was not incredibly intelligent. It was a totally phony story".