When does Espionage become an Act of War?

Following the revelations last month that the Democratic National Committee’s emails were hacked, and the likelihood that the source of attack comes from Russia, questions are raised on whether this constitutes foreign meddling of the U.S. presidential elections process. And if so, how should the U.S. government respond? Where does the practice of espionage becomes an act of war? Elina Noor, director of foreign policy and security studies at the Institute of Strategic and International Studies, explains the intricacies of spying legally.