The Soviets insisted that they had been invited to invade the country, stating that loyal Czechoslovak Communists had told them that they were in need of "fraternal assistance against the counter-revolution". A letter which was found in 1989 proved an invitation to invade did indeed exist. During the attack of the Warsaw Pact armies, 72 Czechs and Slovaks were killed (19 of those in Slovakia) and hundreds were wounded (up to September 3, 1968). Alexander Dubček called upon his people not to resist. He was arrested and taken to Moscow, along with several of his colleagues.