WASHINGTON - US president Barack Obama said in a TV interview set for broadcast later on Sunday that he did not consider the cyber attack on Sony Corp which has been blamed on North Korea to be an act of war, but rather cyber vandalism.Obama and his advisers are weighing up how to respond in kind to the attack, which prompted Sony to withdraw a comedy movie, "The Interview," that had been prepared for release to movie theaters during the holiday season."No, I don't think it was an act of war. I think it was an act of cyber vandalism that was very costly, very expensive. We take it very seriously. We will respond proportionately," Obama told CNN's "State of the Union with Candy Crowley" show.Obama also said his government was considering putting North Korea back on a US list of countries that sponsor terrorism.