On 4 May 2017, at the fourth round of the Astana talks, representatives of Russia, Iran, and Turkey signed a memorandum to establish four " de-escalation zones" in Syria. The largest one of those included the Idlib Governorate and adjoining districts of Hama, Aleppo and Latakia Governorates; the other three zones were set up in the northern rebel-controlled parts of the Homs Governorate , the rebel-controlled eastern Ghouta , and along the Jordan–Syria border . In those areas, combat operations would be halted as of 6 May 2017; it also envisaged suspension of flights of military aircraft in those areas, as well as the creation of conditions for humanitarian access, medical assistance, the return of displaced civilians to their homes and the restoration of damaged infrastructure. The memorandum was concluded for six months and could be extended automatically.  
(2) The opinions of our scientific colleagues on the initial use of these weapons are not unanimous: they range from the proposal of a purely technical demonstration to that of the military application best designed to induce surrender. Those who advocate a purely technical demonstration would wish to outlaw the use of atomic weapons, and have feared that if we use the weapons now our position in future negotiations will be prejudiced. Others emphasize the opportunity of saving American lives by immediate military use, and believe that such use will improve the international prospects, in that they are more concerned with the prevention of war than with the elimination of this specific weapon. We find ourselves closer to these latter views; we can propose no technical demonstration likely to bring an end to the war; we see no acceptable alternative to direct military use.