Russia has said that the use of US long-range missiles by Ukraine will lead to “an appropriate and tangible” response.
A foreign ministry says that such an attack inside Russian territory “will represent the direct involvement of the United States and its satellites in hostilities against Russia”.
President Joe Biden approved the use of the missiles on targets in Russia in a major change of US policy.
Biden’s decision to lift that condition is a significant moment in the war, which marks its 1,000th day this Tuesday.