On April 9, Britain revealed it had tracked and deterred three Russian submarines engaged in a month-long covert operation in the North Atlantic near vital undersea cables and pipelines. Defence Secretary John Healey stated that while there was no evidence of damage to the infrastructure, the operation was disclosed to signal to Russian President Vladimir Putin that such activity would not be tolerated and would have serious consequences. The tracked vessels included an Akula-class submarine, likely acting as a decoy for two specialist GUGI (Main Directorate of Deep Sea Research) vessels designed for sub-surface monitoring and potential sabotage. The UK military, alongside allies Norway and others, deployed warships and aircraft, flying over 450 hours and covering thousands of nautical miles to monitor and warn the Russian submarines. Healey also affirmed Britain's readiness to interdict Russian "shadow fleet" vessels.