Instructions: Answer the question from the given passage. Your answer should be directly extracted from the passage, and it should be a single entity, name, or number, not a sentence.
Input: Passage: On October 6, 1973, Syria and Egypt, with support from other Arab nations, launched a surprise attack on Israel, on Yom Kippur. This renewal of hostilities in the Arab–Israeli conflict released the underlying economic pressure on oil prices. At the time, Iran was the world's second-largest oil exporter and a close US ally. Weeks later, the Shah of Iran said in an interview: 'Of course [the price of oil] is going to rise... Certainly! And how!... You've [Western nations] increased the price of the wheat you sell us by 300 percent, and the same for sugar and cement... You buy our crude oil and sell it back to us, refined as petrochemicals, at a hundred times the price you've paid us... It's only fair that, from now on, you should pay more for oil. Let's say ten times more.' Question: Which oil producer is a close ally of the United States?
Output:
Iran