Mind you, Hanjour was also in this country for several years
1989, 13 years ago, was the year of the Shamir/ Rabin Middle East Peace overtures, intended as a memorial to assassinated Egyptian President Anwar Sadat, and a continuation of the 1978 secret peace accords which precipitated the attack on Sadat's life.
That attempt at an accomodation with Egypt in particular, bypassing the PLO in particular, may have resulted in the execution of plans to insert some long-term assets for a possible strike against the US at that time. Similarly, it could be that the crackdown against those who had murdered Sadat made it prudent for the radical Palestinians to relocate some of their personnel, lest another *Black September* like the one visited upon them by Jordan's King Hussein decapitate their leadership and thin their ranks simultaneously.
Was anything else of similar importance going on in the Middle East circa 1989....?
-archy-/-
I dont know if it has any bearing,but Ayatollah Khomeini died that year.