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:
Iran

Context:
Since the 1979 Revolution, to overcome foreign embargoes, Iran has developed its own military industry, produced its own tanks, armored personnel carriers, guided missiles, submarines, military vessels, guided missile destroyer, radar systems, helicopters and fighter planes. In recent years, official announcements have highlighted the development of weapons such as the Hoot, Kowsar, Zelzal, Fateh-110, Shahab-3 and Sejjil missiles, and a variety of unmanned aerial vehicles (UAVs). The Fajr-3 (MIRV) is currently Iran's most advanced ballistic missile, it is a liquid fuel missile with an undisclosed range which was developed and produced domestically.

Question:
The Fajr-3 missile uses what type of propulsion system?

liquid fuel