R-27U is the first sea-based missile with a cluster (three-unit) warhead. The R-27U missile could be fitted with two types of warheads: an advanced single warhead and a multiple one consisted of three units of the low power class. The creation of a small-size warhead of the low power class was the first step and condition necessary for further development of MIRVs for sea-based missiles. The R-27U cruise engine and onboard control system equipment were upgraded to a limited extent. The firing range of the missile with a single warhead was increased by 20% and that of the missile with a three-unit warhead remained 2,500 km, the firing accuracy was improved by 15%.