an isis bomb on board a russian plane caused its crash in egypt. more on that coming up into but there's another story breaking right now. another sign of rising tensions between the u.s. and china. cnn has learned a chinese submarine stalked a u.s. aircraft carrier in the oceans of the pacific ocean. how much did this worry u.s. officials? >> u.s. officials were concerned about a possible miscalculation. that someone involved in that incident might make a mistake that would lead to shots being fired on the high seas. we've learned tonight that a fast-attack chinese submarine kept the "uss ronald reagan" in its sights while they conducted exercises with the u.s. navy. stalked bay chinese submarine, tonight a chinese attack stalked the "uss reagan" off the coast