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:
Warsaw_Pact

Context:
The eight member countries of the Warsaw Pact pledged the mutual defense of any member who would be attacked. Relations among the treaty signatories were based upon mutual non-intervention in the internal affairs of the member countries, respect for national sovereignty, and political independence. However, almost all governments of those member states were indirectly controlled by the Soviet Union.

Question:
How many countries formed the initial Warsaw Pact membership?

eight