From The Washington Post by Mark Kramer:
The poisoning of former Russian military intelligence officer Sergei Skripal and his daughter in southern England, most likely by Russian intelligence agents, highlights the role of espionage in Russia’s relations with the West. Skripal had been a double agent for the British from the 1990s until he was arrested by Russian security forces in 2004. Britain got him back in a spy swap in 2010. Espionage often generates misconceptions — by virtue of its secrecy.
Media coverage implies, and some researchers believe, that international relationships rise and fall based on spy scandals. Siobhan Martin of the Geneva Center for Security Policy published a study in 2016 arguing that the inherently secret nature of espionage is apt to cause problems: “The Cold War effectively became a ‘spy war’ between US and Soviet intelligence agencies and those of their allies,” she wrote. The Guardian says the Skripal poisoning “has sent UK-Russia relations tumbling.”
But espionage is ubiquitous, and all governments are aware that their opponents — and even their friends and allies — are spying on them. Only rarely do acts of espionage lead to significant tension between states. Even when a spy scandal leads a government to expel another’s diplomats and embassy staff, the furor usually subsides quickly, and staffing levels are restored.