Russian press quotes Nikolai Solovtsov, the commander of the Strategic Rocket Forces, as saying that the RS-24 missile (MIRVed Topol-M) will carry "no fewer than four" warheads. This probably means exactly four - the point here is that there will be more than three warheads, as it was discussed in one of the options. But it also means that the MIRVed Topol-M is unlikely to carry seven warheads as some people suggested.