According to the #genevaconventions, the longer you take and hold #hostages, the longer you sacrifice your own human rights. Israel can use any methods from negotiation to assassination to rescue hostages.
Look it up here:
Israel has broad powers to rescue any hostage according to international law.
"The Convention thus accords a discretion to States in choosing how to respond to #hostage-taking, conceivably extending from negotiation at one end of the spectrum to forcible measures of rescue at the other."