The US believes two Russian jets carried out a series of devastating airstrikes Monday on Syrian aid trucks carrying supplies to a remote region of the country.
Russia and Syria have both denied involvement in the attack that left at least 20 civilians and one Red Crescent staff member dead, but US officials on Tuesday told Reuters that two Russian Sukhoi SU-24 warplanes were in the skies above the convoy at the time of the attack.
The airstrikes forced the UN's humanitarian agency and other aid organizations to suspend convoys to Syria. The convoy was a joint effort between the UN and the Syrian Arab Red Crescent (SARC) and was delivering relief aid to Urem al-Kubra in Aleppo.
About 18 of the 31 trucks in the convoy were estimated to have been hit, as well as a Red Crescent warehouse in the area. Much of the aid was destroyed.
UN Secretary-General Ban Ki-Moon condemned the attack Tuesday as "sickening, savage, and apparently deliberate."
"Just when we think it cannot get any worse, the power of depravity sinks lower," Ban told leaders gathered at the UN General Assembly.
SARC President Dr. Abdulrahman Attar said in a statement Tuesday the organization was "devastated" by the attack.
“We’re totally devastated by the deaths of so many people, including one of our colleagues, the director of our sub-branch, Omar Barakat," said Attar. "He was a committed and brave member of our family of staff and volunteers, working relentlessly to alleviate the suffering of the Syrian people. It is totally unacceptable that our staff and volunteers continue to pay such a high price because of the ongoing fighting."
Also on Tuesday, UN humanitarian aid spokesman Jens Laerke told reporters in Geneva that further aid convoys to the country had been temporarily stopped. "As an immediate security measure, other convoy movements in Syria have been suspended for the time being pending further assessment of the security situation," he said.
Laerke added that the UN had recently received permission from the Syrian regime to deliver aid to besieged areas on the country, Reuters reported.
Also speaking in Geneva, Robert Mardini, the regional director for the International Committee of the Red Cross, described the attack as "very worrying."
"We had something planned in the four towns, but for now it is put on hold to reassess the security conditions," he said.
While no one has been held formally responsible for the attack yet, a video posted by the Syrian Civil Defense Force — also known as the White Helmets — shortly after the attack blamed the Syrian government.
''Today, at 7:12 p.m., regime helicopters targeted a Syrian Red Crescent warehouse," the video's caption said. "A total of four regime helicopters targeted it with 8 barrel bombs."
"Russian aircraft then struck the location with cluster bombs, preventing the civil defense from reaching the location of the attack, giving first aid to those requiring it and removing the dead bodies," the caption continued.
On Tuesday, the Kremlin denied Russian or Syrian government aircraft were responsible for the strike on the convoy, according to the Interfax news agency.
"I am deeply concerned at the breaking reports that the UN/SARC inter-agency convoy to Big Orem was hit this evening," Stephen O'Brien, the head of the UN's humanitarian aid coordination agency, said in a statement soon after the attack on Monday.
"I call on all parties to the conflict, once again, to take all necessary measures to protect humanitarian actors, civilians, and civilian infrastructure as required by international humanitarian law."
The attack came just hours after the Syrian government declared a ceasefire between their forces and rebels to be at an end. The ceasefire, which lasted a week, was part of an agreement brokered by the United States and Russia.
It also comes just days after the US said it was likely that it and several other aircraft in its coalition had mistakenly hit Syrian soldiers in an airstrike.
"We received devastating news about one of the Syrian Arab Red Crescent structures in rural Aleppo coming under attack," Stephen Ryan, a spokesperson for the International Federation of Red Crosses, told BuzzFeed News via email.
"The situation on the spot is very chaotic, and we are deeply shocked that humanitarian workers and missions have yet again suffered from the brutality of this conflict."
The delivery of aid to civilians has been an issue that has plagued the crisis nearly since it first began in 2011. The United Nations Security Council has passed several resolutions demanding that the Syrian government allow the free flow of humanitarian supplies to those in need, but several cities have been under siege.