Worrying about Yemen is a way not to worry about the insoluble problems of Afghanistan and Pakistan.
In other words, they were not going to let the most insoluble problems trump what could be achieved.
Bennett says the conflict with the Palestinians is “insoluble” and sounds almost happy about it.
It was a tacit conviction of the learned during the Middle Ages that no such thing as an insoluble question existed. There might be matters that presented serious difficulties, but if you could lay them before the right man -- some Arab in Spain, for instance, omniscient by reason of studies into the details of which it was better not to inquire -- he would give you a conclusive answer. The real trouble was only to find your man. [Gertrude Bell, "The Desert and the Sown," 1907]
insoluble in·sol·u·ble (ĭn-sŏl'yə-bəl)