Negotiation and Conflict Resolution

In a hostage crisis, is it ethical for a government to agree to grant a terrorist immunity if he releases the hostages, even though the government has every intention of capturing and prosecuting the terrorist once his hostages are released? 

Few Refference ::

 Davis, U. (2020). The role of ethics and national culture. In U. D. Provost, Organizational Behavior (p. 10.6). Califorina: Mind Touch. 

Charlinda Santifort, & Todd Sandler. (2013). Terrorist success in hostage-taking missions: 1978-2010. Public Choice, 156(1/2), 125. https://doi.org/10.1007/s11127-012-0008-z

Navin A. Bapat. (2006). State Bargaining with Transnational Terrorist Groups. International Studies Quarterly, 50(1), 213.