“All parties in this conflict have an obligation under international humanitarian law to take every measure to ensure civilians and civilian objects are protected,” UN Under-Secretary-General for Humanitarian Affairs and Emergency Relief Coordinator Stephen O’Brien told the 15-member body by teleconference this morning.He called it “unacceptable” that health facilities were being hit, referring to an attack on 24 February when Coalition air strikes reportedly destroyed a health centre in Bidbadah district of Marib Governorate, and 1 March airstrikes that reportedly landed within 20 meters of a hospital in Sa’ada.“It is critical that the parties make guarantees that these locations will be protected,” Mr. O’Brien added, including as “protected places” sites such as hospitals, schools and homes, which he said continue to be hit by all parties.Since the start of the conflict, more than 2,000 children have been killed or injured in the fighting, Mr. O’Brien said.In the past week, for example, six children were among the 30 or so people killed in an apparent air strike on a busy market in Nahem district of Sana’a Governorate. An additional 40 people were injured. UN Secretary-General Ban Ki-moon is among those who have called for a prompt and impartial investigation into the incident on 27 February. Challenges to aid deliverySuch attacks have contributed to a security situation across much of the country which is “rapidly deteriorating,” said Mr. O’Brien, citing an absence of political negotiations to end the conflict. He cited “regular” attacks by parties including Al Qaeda in the Arabian Peninsula, the so-called Aden and Abyan branch of the Islamic State in Iraq and the Levans (ISIL) and local militants, against segments of the Yemeni Government.Intense fighting in parts of the country is restricting the UN’s ability to deliver assistance, the senior UN official warned, highlighting also the impediments caused by a proliferation of checkpoints and communication gaps in command and control lines within armed groups. “Agreements and guarantees reached at the national level [are] not necessarily communicated downstream to the individuals at checkpoints,” he said. “Despite permission to move trucks are often held up and sometimes delayed for days or even weeks,” he added. Bureaucratic requirements imposed by Houthi authorities also delay and impede the delivery of aid, he noted. Of particular concern is a delay since October 2015 for a UN agency Emergency Food Security and Nutrition Assessment that is due to be done over three months by the UN World Food Programme (WFP), with the UN Food and Agriculture Organization (FAO) and the UN Children’s Fund (UNICEF).Despite the challenges, UN agencies and partners remain committed to expanding its overall response to 13.4 million people throughout Yemen. To achieve this, the Yemen Humanitarian Response Plan for this year has appealed for $1.8 billion. Protecting civilian infrastructureIn his briefing today, Mr. O’Brien also called on all parties to ensure protection of civilian infrastructure, including shipping ports and associated equipment.In recent months, there has been a significant increase in fuel and other life-saving imports through Yemeni ports: “It is critical that every effort be made by all Member States directly concerned to encourage, and not hinder, that trend.” The Coalition and the United Nations are due to finalize this week the nominations for the UN Verification and Inspection Mechanism (UNVIM), instituted at the request of the Government of Yemen. The Mechanism is intended to expedite legitimate commercial imports of fuel, and other critical commodities, such as food and medicines.Mr. O’Brien’s briefing comes just weeks after UN Special Envoy Ismail Ould Cheikh Ahmed urged the Council and the wider international community to support the effort to secure a cessation of hostilities and open a new round of talks that could open the way to ending the year-long conflict between various factions. Mr. Ould Cheikh Ahmed also briefed the Council today. He spoke by teleconference in the closed consultation session that followed the open meeting.