On 25 September, Seoul was recaptured by UN forces. US air raids caused heavy damage to the KPA, destroying most of its tanks and much of its artillery. KPA troops in the south, instead of effectively withdrawing north, rapidly disintegrated, leaving Pyongyang vulnerable. During the general retreat only 25,000 to 30,000 KPA soldiers managed to reach the KPA lines. On 27 September, Stalin convened an emergency session of the Politburo, in which he condemned the incompetence of the KPA command and held Soviet military advisers responsible for the defeat.