Tamper-respondent assemblies are provided which include a circuit board, an enclosure assembly mounted to the circuit board, and a pressure sensor. The circuit board includes an electronic component, and the enclosure assembly is mounted to the circuit board to enclose the electronic component within a secure volume. The enclosure assembly includes a thermally conductive enclosure with a sealed inner compartment, and a porous heat transfer element within the sealed inner compartment. The porous heat transfer element is sized and located to facilitate conducting heat from the electronic component across the sealed inner compartment of the thermally conductive enclosure. The pressure sensor senses pressure within the sealed inner compartment of the thermally conductive enclosure to facilitate identifying a pressure change indicative of a tamper event.