A/HRC/28/68/Add.1 recovery. The Rapporteur also takes note of the explanation provided by the Government regarding the reasons for her transfer. 645. While the Rapporteur remains concerned about the health of Ms. Dung and the reasons for transferring Ms. Dung to a prison in the north of the country, the Rapporteur concludes that the Government of Viet Nam has not violated Ms. Dung’s right to be free from torture or cruel, inhuman or degrading treatment, as provided by articles 1 and 16 of the CAT. However, the Rapporteur implores the Government of Viet Nam to continue to monitor the health of Ms. Dung to ensure that she receives the medical care that she is entitled to. 646. On the other hand, the Rapporteur considers unsatisfactory the Government’s reply regarding the solitary confinement that Ms. Dung has been allegedly subjected to. Solitary confinement is an extreme measure that inflicts serious mental pain and suffering on the inmate. For that reason, if used for disciplinary reasons it should be only for extreme breaches of prison rules and for limited time. The Rapporteur urges the government of Viet Nam to clarify the duration and other conditions of any period of isolation to which Ms. Dung may have been subjected. If she has been placed in solitary confinement, the Rapporteur would also wish to know the reasons and purposes of the measure and what procedural guarantees were afforded to her. The Special Rapporteur reserves his opinion of whether this aspect of the case constitutes a violation of Viet Nam’s international obligations until after receiving this additional information. Yemen (a) JUA 19/12/2013 Case No. YEM 4/2013 State Reply: None to date Allegations concerning the death in custody of Mr. Omar Zayd Hassan Soufyan in the Political Security Prison in Sana’a on 22 October 2013. 647. The Special Rapporteur regrets that the Government of Yemen has not replied to the present communication, thereby failing to cooperate with the mandate issued by the Human Rights Council in its resolution 25/13, and to comply with its obligation, under international customary law, to investigate, prosecute and punish all acts of torture and other cruel, inhuman or degrading treatment or punishment, as codified, inter alia, in the Convention against Torture (CAT). 648. Mr. Soufyan’s death apparently took place in the context of a demonstration in the prison where he was held. His relatives were denied visits and then received the corpse. They found traces of severe mistreatment and requested an autopsy, which was denied. 649. In the absence of information to the contrary, the Rapporteur concludes that there is substance in the allegations presented in the initial communication, reiterated above, and thus, that the Government of Yemen, by failing to protect the physical and psychological integrity and prevent the death in detention of Mr. Soufyan, has violated his right to be free from torture or cruel, inhuman or degrading treatment, as provided by articles 1 and 16 of the CAT. In addition, the Government has failed to live up to its obligation to investigate each act of torture and to prosecute and punish those responsible. (b) JAL 20/12/2013 Case No. YEM 5/2013 State Reply: None to date Allegations concerning a lethal air strike in the Republic of Yemen on 12 December 2013, allegedly involving the use of armed drones belonging to the authorities of the United States of America. 650. The Special Rapporteur regrets that the Government of Yemen has not replied to the present communication, thereby failing to cooperate with the mandate issued by the Human Rights Council in its resolution 25/13, and to comply with its obligation, under international customary law, to investigate, prosecute and punish all acts of torture and 106