PRAGUE (AP).- A pink tank has temporarily returned to the heart of Prague to mark the 20th anniversary of the Soviet troops’ withdrawal. Tank No. 23 was originally put on display on a Prague square in 1945 to commemorate the liberation of Czechoslovakia by the Red Army after the WWII occupation by Nazi troops. For many, it became a symbol of the 1968 Soviet-led invasion that crushed the liberal reforms of Alexander Dubcek and ended an era known as the Prague Spring. David Cerny, a Czech visual artist painted the tank pink with friends in April 1991. The Soviet troops left by the end of June that year. The tank was taken to Prague from a military museum Monday to be placed on a pontoon on the Vltava river to kick off commemorative events, marking the troops’ withdrawal.