Russian space forces launched a Kosmos 3M booster Tuesday with a pair of classified military satellites aboard from the Plesetsk Cosmodrome.

Liftoff of the Kosmos 3M was at 1050 GMT (6:50 a.m. EDT) Tuesday from Russia's northern launch site.

The two military payloads successfully reached orbit and are officially known at Kosmos 2400 and 2401 in the Russian defence ministry's discreet naming scheme.

Thursday's flight marked the 37th space launch of 2003 on a worldwide basis, the fifth of the year from Plesetsk and the second mission for a Kosmos 3M rocket this year.

This launch took the place of an earlier scheduled commercial Kosmos 3M flight that was to have orbited a number of small satellites, including several for the international Disaster Monitoring Constellation lead by the British Surrey Satellite Technology Limited organization.

Originally set for late July, that launch was put off until September 26 to make way for the Russian military's needs to loft Kosmos 2400 and 2401 for an undisclosed reason.