America first gave Ukraine HIMARS rocket launchers in the summer of 2022, though equipped only with shorter-ranged GPS -guided rockets. In late 2023, after over a year of debate, it relented and provided the 300km-range ATACMS.

While many questions remain, the move by the US to green light the use of missiles inside Russia will no doubt lead US allies to do the same – and provoke Russia’s ire.

The Kremlin warns Kyiv's use of such missiles would mark an escalation in the conflict, hours after Joe Biden gives the green light.