A Russian Rockot booster propelled three military satellites into orbit early Monday during an unannounced launch, marking the converted ballistic missile's second flight this year.

The 95-foot-tall rocket lifted off Monday morning, local time, from Complex 133 at the Plesetsk Cosmodrome in Kazakhstan.

The Rockot is a modified two-stage SS-19 missile built to deliver nuclear payloads to distant targets. Engineers converted the wartime weapon to a peacetime space launcher by adding a third stage to inject satellites into orbit.

The Breeze KM upper stage put three secret spacecraft in a a circular 932-mile-high orbit with an inclination of 82.5 degrees, according to tracking data.

The satellites were deployed at about 0310 GMT Monday, according to Russian news reports.

Russian news agencies provided few details about the satellites, but officials said they would be operated for the Russian military.

The new spacecraft will be named Kosmos 2451, Kosmos 2452 and Kosmos 2453, reports said.

Monday's launch was the second flight this year for the Rockot vehicle, which also launched a European science satellite in March.

Another Rockot is scheduled to launch two more European payloads in early November.