In this task, we ask you to write a question that asks about "event duration", based on a given sentence. The question will likely start with "How long". Your question should be answerable based on the common knowledge of how long certain events usually last. Don't create questions which have explicit mentions of answers in the text. Instead, it has to be implied from what is given. In other words, we want you to use "instinct" or "common sense". Note that the written questions are not required to have a single correct answer.

Sentence: One result was two NSC-led interagency trips to Persian Gulf states in 1999 and 2000.
How long did the trips last?