(CNN) Who was behind the sabotage of France’s railway network? Here’s what we know.

Absent  concrete clues, there is a persuasive argument for Russian responsibility:

• Known Russian intent to disrupt the Olympics. See (PBS) French authorities detain Russian man accused of plotting to ‘destabilize’ Olympics.
• Deniability serves Russian goals, failing to provide the adversary with a logical platform for escalation or retaliation.
• The modus serves the  known Russian tactic of inducement of societal malaise.
• Synchronization over great distance.
• Freedom to execute at a time of maximum impact. Less sophisticated  entities lack undetectable loitering capability.
• Little or no forensic evidence.
• Conformity with other notable successes in industrial sabotage.

Russia’s covert operations in Western Europe have two distinct tracks:

• Low budget, amateurish, espionage.
• High budget, professional industrial sabotage.

The rail attacks exemplify Russian covert expertise.