US President Donald Trump on Sunday said Special Envoy Steve Witkoff may travel to Russia, potentially on Wednesday or Thursday, as he warned that he would impose sanctions if Moscow does not agree to a ceasefire in the war in Ukraine before Friday.

"There'll be sanctions, but they seem to be pretty good at avoiding sanctions," Trump told reporters in New Jersey.

"They're wily characters and they're pretty good at avoiding sanctions, so we'll see what happens."

"Is there anything [Russia] can do to avoid sanctions at this point?" a reporter asked. "Yeah, get a deal where people stop getting killed," Trump responded.

"Have those nuclear submarines been deployed yet to face Russia?" a reporter asked.

"They are in the region, yeah, where they have to be," Trump answered.

Trump orders nuclear submarines to reposition near Russia

This was in reference to Trump on Friday saying that he had ordered two nuclear submarines to be positioned in regions near Russia in response to threats from former Russian president Dmitry Medvedev.

"I have ordered two Nuclear Submarines to be positioned in the appropriate regions, just in case these foolish and inflammatory statements are more than just that," Trump said in a post on Truth Social.

Ohio-class ballistic missile submarine USS Tennessee, part of the US nuclear deterrent, transits the St. Marys Channel as it departs Naval Submarine Base Kings Bay, Georgia in this February 6, 2013 handout photo.
Ohio-class ballistic missile submarine USS Tennessee, part of the US nuclear deterrent, transits the St. Marys Channel as it departs Naval Submarine Base Kings Bay, Georgia in this February 6, 2013 handout photo. (credit: REUTERS/MASS COMMUNICATION SPECIALIST 1ST CLASS JAMES KIMBER/U.S. NAVY/HANDOUT VIA REUTERS)

Trump and Medvedev, who is deputy chairman of Russia's Security Council, traded taunts in recent days after Trump on Tuesday said Russia had "10 days from today" to agree to a ceasefire in Ukraine or be hit, along with its oil buyers, with tariffs.

Moscow, which has set out its own terms for peace in Ukraine, has shown no sign that it will comply with Trump's deadline.

This is a developing story.