Complex sentence: At those levels, the ICBM begins to approach the manned bomber in terms of accuracy; a small upgrade, roughly doubling the accuracy of the INS, would give it the same CEP as the manned bomber.
Split into simpler sentences: At those levels, the ICBM begins to approach the manned bomber in terms of accuracy. A small upgrade, roughly doubling the accuracy of the INS, would give it the same CEP as the manned bomber.