UNITED STATES President Donald Trump warned Russia on Sunday that he may send Ukraine long-range Tomahawk missiles if Moscow doesn't settle its war there soon.

The president suggested that he could be ready to increase the pressure on Vladimir Putin's government using a key weapons system.

“I might say: ‘Look: if this war is not going to get settled, I’m going to send them Tomahawks’,” President Trump told reporters.

“The Tomahawk is an incredible weapon, very offensive weapon. And honestly, Russia does not need that.”

President Trump also said: “I might tell them that if the war is not settled — that we may very well.” He said: “We may not, but we may do it. I think it's appropriate to bring up.”

His comments came after President Trump spoke with Ukrainian President Volodymyr Zelensky and the US president said that he mentioned possibly sending Tomahawks during that conversation.

His suggestions followed Russia having attacked Ukraine’s power grid overnight, part of an ongoing campaign to cripple Ukrainian energy infrastructure before winter. 

Moscow also expressed “extreme concern” over the US potentially providing Tomahawk cruise missiles to Ukraine.

President Putin himself has previously suggested that the US supplying long-range missiles to Ukraine will seriously damage relations between Moscow and Washington.