Responding to malicious cyber operations: state countermeasures

Understanding the application and implications of countermeasures in a cyber context.

Research event, Panel Recording
23 May 2024 — 5:00PM TO 6:30PM
Chatham House and Online

Event recording

Exploring the application of international law on countermeasures in the cyber context.

With malicious cyber operations increasingly launched from one country to another, states are looking for effective ways to respond consistently with international law. 

Governments regularly resort to unfriendly but lawful acts of retorsion in the cyber context, such as the US expelling diplomats and imposing sanctions following the Solar Winds hack. International law also allows states to take ‘countermeasures’ in response to wrongful acts in cyberspace and beyond.

Countermeasures are responses that would normally be unlawful but are justified when taken to stop and/or repair acts that violate international law. 

The use of countermeasures in cyberspace is marred by uncertainty and significant debates about the exact conditions for taking those measures. This includes controversies about how those conditions apply in the cyber context – a challenge compounded by the speed, scale and covertness of cyber operations.

This discussion explores the application of the international law on countermeasures in the cyber context, and its implications for response options to malicious cyber operations. It also launched the research paper Countermeasures in international law by Chatham House’s International Law Programme.

Key questions discussed include:

  • What are countermeasures and what is their significance as a policy option in cyberspace?
  • What are the conditions for taking countermeasures under international law generally and in cyberspace?
  • What are the key technical and legal challenges around the application of those conditions in the cyber context?
  • What are ‘collective’ or ‘third-party’ countermeasures, what is their significance in cyberspace and to what extent are they lawful under international law?
  • Can different states take countermeasures against Russia’s invasion of Ukraine?
  • What are the implications of allowing different kinds of countermeasures as response options to malicious cyber operations?

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