Concerned for his safety, on 20 December Amin moved from the Presidential Palace, located in the centre of Kabul, to the Tajbeg Palace, which had previously been the headquarters of the Central Army Corps of the Afghan military. The palace was formidable, with walls strong enough to withstand artillery fire. According to Rodric Braithwaite, "its defences had been carefully and intelligently organised". All roads to the palace had been mined, with the exception of one, which had heavy machine guns and artillery positioned to defend it. To make matters worse for the Soviets, the Afghans had established a second line of defence which consisted of seven posts, "each manned by four sentries armed with a machine gun, a mortar, and automatic rifles". The external defences of the palace were handled by the Presidential Guard, which consisted of 2,500 troops and three T-54 tanks. Several Soviet commanders involved in the assassination of Amin thought the plan to attack the palace was "crazy". Although the military had been informed by the Soviet leadership through their commanders, Yuri Drozdov and Vasily Kolesnik, that the president was a "CIA agent" who had betrayed the Saur Revolution, many Soviet soldiers hesitated; despite what their commanders had told them, it seemed implausible that Amin, the leader of the PDPA government, was an American double agent. Despite several objections, the plan to assassinate Amin went ahead.