Sir Richard Moore and Bill Burns did not list examples but there has been a spate of mysterious sabotage and arson attacks on infrastructure in the UK, Germany and in the Baltics.

Russia is waging a “reckless campaign of sabotage” across Europe, the heads of MI6 and the CIA have warned in their first-ever joint remarks.

Sir Richard Moore and Bill Burns also said the UK and the US faced an “unprecedented array of threats”, and said the entire world order was under the most serious strain since the Cold War.

In a newspaper article, the spymasters pointed to Vladimir Putin’s war in Ukraine, while also describing China as “the principal intelligence and geopolitical challenge of the 21st century”.