Well, think about it: An asteroid, similar to the size of Everest (Like the one 65 million years ago), would hit the Earth, cause tsunamis, incinerate foliage, rain molten rock, and generally cause a bad day. But a hundred million pebbles raining down from space would cause casualties and destruction, but wouldn't have the same "massive impact" aftereffects. And if the asteroid was big enough, it could affect the Earth's orbit and spin, leading to large climate changes. If I were to choose, I'd say we nuke it. Perhaps several times.