<P> On October 31, 1979 Soviet informants to the Afghan Armed Forces who were under orders from the inner circle of advisors under Soviet premier Brezhnev, relayed information for them to undergo maintenance cycles for their tanks and other crucial equipment . Meanwhile, telecommunications links to areas outside of Kabul were severed, isolating the capital . With a deteriorating security situation, large numbers of Soviet Airborne Forces joined stationed ground troops and began to land in Kabul on December 25 . Simultaneously, Amin moved the offices of the president to the Tajbeg Palace, believing this location to be more secure from possible threats . According to Colonel General Tukharinov and Merimsky, Amin was fully informed of the military movements, having requested Soviet military assistance to northern Afghanistan on December 17 . His brother and General Dmitry Chiangov met with the commander of the 40th Army before Soviet troops entered the country, to work out initial routes and locations for Soviet troops . </P> <P> On December 27, 1979, 700 Soviet troops dressed in Afghan uniforms, including KGB and GRU special forces officers from the Alpha Group and Zenith Group, occupied major governmental, military and media buildings in Kabul, including their primary target--the Tajbeg Presidential Palace . </P> <P> That operation began at 19: 00 hr., when the KGB - led Soviet Zenith Group destroyed Kabul's communications hub, paralyzing Afghan military command . At 19: 15, the assault on Tajbeg Palace began; as planned, president Hafizullah Amin was killed . Simultaneously, other objectives were occupied (e.g., the Ministry of Interior at 19: 15). The operation was fully complete by the morning of December 28, 1979 . </P> <P> The Soviet military command at Termez, Uzbek SSR, announced on Radio Kabul that Afghanistan had been liberated from Amin's rule . According to the Soviet Politburo they were complying with the 1978 Treaty of Friendship, Cooperation and Good Neighborliness and Amin had been "executed by a tribunal for his crimes" by the Afghan Revolutionary Central Committee . That committee then elected as head of government former Deputy Prime Minister Babrak Karmal, who had been demoted to the relatively insignificant post of ambassador to Czechoslovakia following the Khalq takeover, and announced that it had requested Soviet military assistance . </P>

When did the soviet union take over afghanistan