Russian involvement in European attacks assessed as ‘credible’, security sources say

But sources stress that without actual evidence, such hybrid attacks provide perpetrators with “plausible deniability”.

Irish security services are keeping a close watch on developments as they update their threat assessment for next week’s major political events in Dublin.

The Irish Examiner understands that security services assess the likelihood that Russian intelligence is behind these incidents as “credible” — with the caveat that investigations by European police and cyber agencies will take time.

Extensive contact is taking place among European intelligence and cyber agencies to share and analyse information.

“The key challenge for intelligence services is that plausible deniability is interwoven into the design of these attacks.”