The Kremlin said on Monday it was anticipating “important” talks with Donald Trump’s special envoy, Steve Witkoff, later this week, ahead of the US president’s looming deadline to impose fresh sanctions on Moscow if it does not make progress towards a peace deal with Ukraine.

Trump confirmed on Sunday that special envoy Steve Witkoff will visit Russia, likely on “Wednesday or Thursday”, where he is expected to meet President Vladimir Putin.

Speaking to reporters, Trump also said that two nuclear submarines he deployed following an online row with former Russian president Dmitry Medvedev were now “in the region”.

Trump has not said whether he meant nuclear-powered or nuclear-armed submarines. He also did not elaborate on the exact deployment locations, which are kept secret by the US military.

Russia, in its first comments on the deployment, urged “caution”.

The nuclear sabre-rattling came against the backdrop of a deadline set by Trump at the end of next week for Russia to take steps towards ending the Ukraine war or face unspecified new sanctions.