A/HRC/39/43 Proportionality Assessment 30. The coalition has imposed a complete effective closure of Sana’a airport to all commercial flights since August 2016, including travel for individuals requiring immediate medical treatment abroad. The only exceptions have been flights arranged by Saudi Arabia. The coalition has provided no explanation of the military necessity of closing the airport completely. In the absence of such an explanation, the closure of Sana’a International Airport appears to violate the proportionality rule of international humanitarian law. Conclusion 31. Based on the evidence available, there are reasonable grounds to believe access restrictions and de facto blockades violate the proportionality rule of international humanitarian law.19 While this finding relies on an evolved understanding of the application of the principles of international humanitarian law, it is consistent with those principles. Given the grave consequences of these restrictive measures for the civilian population in Yemen, the Experts consider this approach warranted. 19 This finding is without prejudice to the application of the other rules of international humanitarian law, including the principle of precautions in attack. 33