Russia on Monday, 21 January, threatened retaliation after the European Union slapped sanctions on Russian military intelligence chiefs over the nerve agent attack on former Russian spy Sergei Skripal in Britain.
"We reserve the right to take retaliatory measures over this unfriendly step," the Russian foreign ministry said in a statement.
Kostyukov took over the GRU after the death of his predecessor Igor Korobov last November.
Moscow said the claims did not "stand up to criticism." "An information campaign unleashed by the British authorities over this case primarily has a domestic agenda," the Russian foreign ministry said.
"It is telling that its new round coincides with a new crisis in Brexit talks."
"The European Union is demonstrating its euro-solidarity, which is used to replace the absence of evidence," he told Russian news agencies.
"It is strange that this euro-solidarity is being shown towards the UK which is scandalously leaving the EU and which is leaving the EU with the Salisbury scandal one on one."
Before the sanctions were announced, Kremlin spokesperson Dmitry Peskov said earlier on Monday that the new EU measures were unsubstantiated.
(Published in an arrangement with PTI.)
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