Stalin launched the "dekulakization" program, which was centered in Ukraine. Soviet police took away the kulak's homes and possessions, and either shot or exiled those who resisted. They also imposed heavy grain taxes, which left the kulaks to starve. Some families killed their livestock and burned their houses down instead of handing them to the Soviets. A system of international passports prevented the Ukrainians from leaving their towns, and to stop them from crossing the border and leaving the country. All foreign aid from the United States and Europe were denied at the border. Even journalists were not allowed inside, because the Soviets feared that they would reveal the crimes committed. Ukrainians were then sent to labor camps in unheated trains, with little food.