That is not correct. Yo may be referring to another test. In this test, an SS-25 TOPOL (redesignated SS-27) was used.
SS-N-23 (SKIFF)
SS-25 (SICKLE)
SS-19 (STILLETO)
There was no SS-27 launched. The SS-27 is the TOPOL-M. The SS-25 is the TOPOL (NATO CODENAME SICKLE)
The reason why it was an SS-19 STILLETO that launched the hypersonic vehicle is due to the specific conditions of the START I protocol. The Russians announced to the west that ICBM/SLBM would be launched and that one of those would be carrying a hypersonic research vehicle. The first missile to be launched under the protocol was the SS-19 STILLETO from Tyuratum. The Russians provided no impact areas on the Kamchatka peninsula for this test because the purpose of the missile was to boost the hypersonic research vehicle. The missile only flew a partial ballistic trajectory and then the scramjet powered hypersonic vehicle detached to conduct its mission. The second missile to launch was the SS-N-23 (SKIFF) from the DELTA-IV which impacted on the Kamchatka peninsula. The third missile to launch was the SS-25 (SICKLE from Plesetsk which also impacted on the Kamchatka peninsula as per treaty conditions. As to the type of hypersonic vehicle the SS-19 was carrying it was more than likely an IGLA or derivative:
"Igla RSA also is pursuing the Igla vehicle, an integrated engine/airframe concept similar to the US Hyper-X that employs a hydrogen scramjet. The vehicle is 5m/16.4ft in length and designed for mach 5-14 speeds. It is to be boosted to speed by launch aboard an SS-18 or SS-19 ICBM. A date has not yet been set for an Igla test flight"
"FIRST FLIGHT OF IGLA HYPERSONIC AIRCRAFT SCHEDULED FOR 2004
According to the representatives of the Central Institute of Aircraft Engine Building (TsIAM), the first flight of the Igla hypersonic aircraft, currently under development in Russia is scheduled for the year 2004. The Igla is designed to carry out research and testing of a scramjet. This engine runs on liquid hydrogen and is planned to power the future advanced space passenger-carrying and military aircraft. These aircraft will offer several times lower specific cost of putting payloads into orbit. Presently, this cost makes up US$ 8-30,000.
The Voronezh Khimavtomatika Design Bureau has already produced a single scramjet which is planned to be used for flight tests at M=6.5
TsIAM plans to demonstrate a full-scale mockup of the Igla at the MAKS-99 Air Show in Zhukovsky (Moscow region).
In the words of the representative of the institute, all the previous works on the scramjet have been carried out both with domestic (the Russian Space Agency) and foreign customers: France, USA. In the framework of this programme, a US$ 2 million contract has been signed with "a number of the US governmental organisations".
However, the Igla programme may be implemented only in case adequate financing is provided, the representative stressed. The project cost is about 1 billion roubles (US$ 40 million). As far as there is no such money in the Russian budget, the scramjet developers are planning to attract additional, possibly foreign investments. The US plans to spend US$ over 100 million on similar programme."
The plans to launch the HGV from an SS-19 were even released in open source many years ago:
"The Mashinostroenie NPO showed, in addition to its Almaz program, its Strela mini-launcher project and Igla experimental hypersonic vehicle. Like the Rockot, the Strela rocket is a derivative of the UR-100N (alias SS-19) missile. It is the subject of an agreement with Khrunichev. Launched from a Baykonur or Plessetsk silo, it can place payloads of 1.2 mt to 1.8 mt in circular orbits at 300 to 1,100 km, inclined at 63[DEG]. The Igla demonstrator is part of the Oriol national program devoted to the study of hypersonic flight. Weighing 2 mt, it is to be launched by the SS-19 missile over a suborbital trajectory. TsIAM's [Central Institute of Aviation Engine Building] liquid hydrogen scramjet is designed to operate from Mach 6 to Mach 14 at an altitude of 45 km “
A paper on the IGLA:
Two more clues in open source to the fact that the SS-19 was the HGV carrier:
ITAR-TASS quoted Putin as saying that the SS-19 missile launched at Baikonur "has no competition" when it comes to breaking through potential defense mechanisms."We are talking about a very dangerous weapon with serious potential," Putin said.
A spokesman for the Strategic Missile Troops, Lieutenant Colonel Vadim Koval, said the SS-19 launch "resolved a number of experimental tasks applicable to ground-based strategic missile systems."