Definition: In this task, you will be presented with a passage and have to answer a question based on your understanding of the events inferred from the passage. Try to find the best answer that is most likely to fill in "_". Note that the URLs in the text have been replaced with [Link].
Input: Washington (CNN) The Obama administration secretly arranged a plane delivery of $400 million in cash on the same day Iran released four American prisoners and formally implemented the nuclear deal, US officials confirmed Wednesday. President Barack Obama approved the $400 million transfer, which he had announced in January as part of the Iran nuclear deal. The money was flown into Iran on wooden pallets stacked with Swiss francs, euros and other currencies as the first installment of a $1.7 billion settlement resolving claims at an international tribunal at The Hague over a failed arms deal under the time of the Shah.Obama approved the $400 million transfer, which he announced in JanuaryIt was the first payment of a $1.7 billion settlementThe funds had been contested since the 1979 Iranian revolution 
 Question:It was something that was intended to, as I am told, pay back Iran for contracts that were canceled when the _ fell."

Shah