Talk of mounting nuclear readiness towards Russia could overshadow more trifling domestic matters, like the Epstein scandal, for instance.

It comes after Dmitry Medvedev, who is now deputy chair of Russia's Security Council, told the US president to remember Moscow had Soviet-era nuclear strike capabilities of last resort.

In a social media post, the president described the move as a deterrent prompted by threats by a former Russian leader. It is unclear if any submarines did actually change position.