The Kremlin has responded with predictable theatre to comments from foreign secretary David Cameron after he said Ukraine is free to use weapons supplied by Britain to launch strikes inside Russia.

That theatre was both diplomatic, with the British ambassador summoned to the foreign ministry in Russia on Monday to warn of retaliation, and nuclear, as Moscow announced it would be holding exercises involving tactical nuclear weapons in the near future in order to remind the world yet again that it has them.

During his recent visit to Kyiv, the foreign secretary stated clearly that it was Ukraine’s decision how to use British weapons, and said Kyiv “absolutely has the right to strike back at Russia”.