A Proton-K booster launched a Russian Cosmos military satellite into orbit early Wednesday from the Baikonur cosmodrome in Kazakstan.
The booster is the same one to be used to launch the Russian-built Zvezda living module for the International Space Station next week.
Two failed Proton launches last year raised concerns about the rocket's reliability. Space officials say they have fixed a problem with the second-stage engines, and there have been several successful Proton launches this year.
The failures contributed to delays in launching Zvezda, which is more than two years behind schedule.