The launch of an SES telecommunications satellite slated to fly atop an International Launch Services (ILS) Proton rocket, which had been scheduled for Jan. 28, has been postponed due to an unspecified technical problem with the launch vehicle, ILS announced Jan. 27.

Reston, Va.-based ILS said the rocket would be removed from the launch pad at the Baikonur Cosmodrome in Kazakhstan and returned to the ILS integration facility. The delay marks the second time the SES-4 satellite, built by Space Systems/Loral for Luxembourg-based SES, has been postponed in recent weeks. Last month, ILS pushed back a Dec. 26 launch after engineers discovered a problem with the avionics unit of the rocket’s Breeze M upper stage during preflight processing. The vehicle was rolled back from its launch pad and de-stacked, and the affected unit was replaced.

“The rescheduled date and time of the launch will be determined at a later date following corrective measures and additional testing,” according to the statement.