WASHINGTON - Two Russian warplanes with no visible weaponry flew simulated attack passes near a US guided missile destroyer on April 12 in international waters off Russia, a US official said on Wednesday, describing it as one of the most aggressive acts in recent memory. The flight by the Sukhoi SU-24 warplanes was so close it created 'wake in the water' and was followed by seven passes by Russian KA-27 Helix helicopter taking pictures of the USS Donald Cook, the official said, speaking on condition of anonymity.