A recent shift in U.S. policy has sparked intense debate, as President Joe Biden authorized Ukraine to deploy American long-range missiles, including the Army Tactical Missile Systems (ATACMS), against targets inside Russia.

Biden has committed tens of billions of dollars to Kyiv's war effort, and at the weekend he reportedly ditched a long-standing red line on Ukraine's use of American weaponry to launch attacks deep into Russia. Donald Trump Jr tweeted that the president was trying to "get World War Three going" before his father took office.