Amid heightened concerns over a series of undersea cable disruptions in the Baltic Sea—believed to be caused by anchor draggings—European security officials have been alarmed by the possibility of hybrid attacks targeting critical infrastructure by Russia or China. Adding to the unease, Britain's defense minister issued a warning on Wednesday about a Russian spy ship operating in UK waters. 

UK Defence Secretary John Healey made clear to the House of Commons that a Russian spy ship, Yantar, had been detected in the English Channel and loitered over critical undersea infrastructure. This was first reported by the Financial Times. 

"Russia remains the most immediate and pressing threat to Britain ... and any threat will be met with strength and resolve," Healey said. 

He said the Yantar spy ship had passed through the Strait of Dover and into Dutch waters. 

Healey noted that a Royal Navy submarine surfaced near the Yantar to warn the crew that its every movement would be tracked. 

"I want President Putin to hear this message: 'We see you, we know what you're doing and we will not shy away from robust action to protect this country," the defense official told lawmakers. 

He added: "We will continue to call out the malign activity that Putin directs, cracking down on the Russian shadow fleet." 

Over the past 18 months, three alarming incidents have been reported in which commercial ships traveling to or from Russian ports are suspected of severing undersea cables in the Baltic region.

The question remains whether the three incidents were acts of sabotage or merely just accidents.