You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Josip_Broz_Tito

Context:
One significant consequence of the tension arising between Yugoslavia and Soviet Union, was that Tito fought Yugoslav Stalinists with Stalin's methods. In other words, Aleksandar Ranković and the State Security Service (UBDA) employed the same inhumane methods against their opponents as Stalin did in the Soviet Union against his. Not every person accused of a political crime was convicted and nobody was sentenced to death for his or her pro-Soviet feelings. However this repression, which lasted until 1956, was marked by significant violations of human rights.

Question:
The work of the UBDA was due to tension between Yugoslavia and what country?

Soviet Union