President Vladimir Putin has updated Russia’s nuclear doctrine, two days after his US counterpart Joe Biden granted Ukraine permission to strike targets deep inside Russia with American-made weapons.

Putin lowered the bar for a nuclear attack after the US lifted a ban on Ukraine using long-range missiles. Ukraine carried out its first strike with the weapons.

Sergey Lavrov branded Ukraine's use of ATACMS missiles as proof Kyiv "wanted to escalate" and vowed Moscow will "react accordingly".