With single warhead missiles, one missile must be launched for each target.
A ban on multiple warhead missiles should be considered in Start II, but should not be injected into the current talks.
The penetrations were caused by tandem warhead missiles.
And Mr. Dukakis's opposition to the Midgetman program means he is against the only program under way to develop a single warhead missile.
Among the proposals under review are a new ceiling on the number of multiple warhead missiles deployed in silos.
Under this proposal, single warhead mobile missiles would be allowed.
Stopping China from conducting nuclear tests, he said, would prevent Beijing from fielding a new generation of mobile, multiple warhead missiles.
The accord would also outlaw land-based multiple warhead missiles, which are particularly dangerous because they are considered the most tempting targets in a nuclear crisis.