One of the biggest challenges in Critical Infrastructure Protection or Incident Response is collaboration. Collaboration between the public and the private sector as the private sector is most often running the critical infrastructure; collaboration between different governments as well as incidents do not tend to stop at a country's border.
Now, planning for such a collaboration is one thing but really trying out whether the collaboration really works is another one. Just testing whether all the communication channels come up and can get established is hard by itself.
The US was already running exercises called “Cyberstorm” within the US to test the collaboration and the plans within the US. Now it seems that they are planning to extend that: Next Cyberstorm exercise to stress international cooperation on security. This is a great development and it will be interesting to see what the results will be.