While there was widespread agreement that such a collision would indeed destroy a warhead, there was disagreement on how many rockets would be needed to ensure one hit the warhead. This was exacerbated by uncertainties in the environment they would fly through, which would include the dust and debris of the explosions of the warheads they chose not to intercept. Any such uncertainty requires more rockets, to the point where it was considered unlikely the system would be able to fit into an MX container.
