A/76/135 Letter of transmittal 28 May 2021 I have the honour to submit herewith the consensus report of the Group of Governmental Experts on Advancing responsible State behaviour in cyberspace in the context of international security. The Group was established in 2018 pursuant to operative paragraph 3 of General Assembly resolution 73/266. In this resolution, the General Assembly requested that a group of governmental experts be established in 2019 on the basis of equitable geographical distribution, proceeding from the assessments and recommendations contained in the consensus GGE reports of 2010, 2013 and 2015, to continue to study, with a view to promoting common understandings and effective implementation, possible cooperative measures to address existing and potential threats in the sphere of information security, including norms, rules and principles of responsible behaviour of States, confidence-building measures and capacity-building, as well as how international law applies to the use of information and communications technologies by States. The Secretary-General was requested to submit a report on the results of the study to the Assembly at its seventieth-sixth session. In accordance with the Group’s mandate, an official compendium of voluntary national contributions of participating governmental experts on the subject of how international law applies to the use of ICTs by States will be made available on the website of the United Nations Office for Disarmament Affairs in the original language of submission without translation (A/76/136). In accordance with the terms of the resolution, experts were appointed from 25 States: Australia, Brazil, China, Estonia, France, Germany, India, Indonesia, Japan, Jordan, Kazakhstan, Kenya, Mauritius, Mexico, Morocco, the Netherlands, Norway, Romania, the Russian Federation, Singapore, South Africa, Switzerland, the United Kingdom of Great Britain and Northern Ireland, the United States of America, and Uruguay. The list of experts is appended to the report. The Group held four formal sessions: the first from 9 –13 December 2019 at United Nations Headquarters, the second from 24–28 February 2020 in Geneva, the third in a virtual format from 5–9 April 2021 and the fourth in a virtual format from 24–28 May 2021. The third session of the Group was postponed pursuant to General Assembly decision 75/551 due to the COVID-19 pandemic. The Group nonetheless continued its work during this time through a series of several intersessional informal consultations. As per its mandate, a series of consultations with relevant regional organizations and open-ended consultative meetings with Member States were also held in order to engage in interactive discussions and share views. The Group wishes to express its appreciation for the contribution of the joint Support Team from the United Nations Office for Disarmament Affairs and the United Nations Institute for Disarmament Research. I also take this opportunity to express my personal gratitude to the Government of Brazil for designating me and to the Group for the honour of the chairmanship. I also thank my fellow Experts, my Brazilian colleagues, members of the joint Support Team and the United Nations Secretariat, in particular the High Representative for Disarmament Affairs, for their support and for sharing their great expertise in a constructive spirit of engagement. (Signed) Guilherme de Aguiar Patriota Chair of the Group 21-04030 5/26