Give me a break! Many countries, actually too many to name, including Russia, the U.S.A, China, North Korea, many Arab countries, and also Israel unfortunately, have held foreign citizens without due process or trial. Think Guantanamo Bay re: Islamic terrorists, real or imagined, held by the U.S.A. in barbaric conditions after 9/11.
But when it comes to Israeli hostages, or even situations like the 1972 Munich Olympics massacre of the Israeli Olympic athletes by Black September Islamists, Israel will absolutely retaliate and if there are hostages to rescue in any situation they will do all it takes to rescue them.