BEIRUT -- The World Food Program said its first high-altitude airdrop over the Syrian city of Deir el-Zour, which is under siege from the Islamic State of Iraq and Syria (ISIS), may have been off-target.

WFP spokeswoman Bettina Luescher said in an email late Wednesday that 21 metric tons of "assistance" were dropped, but that the overall operation had faced "technical difficulties."

It was not immediately clear if that meant that the airdrop had missed its target, but Luescher said: "High altitude drops are extremely challenging to carry out and take more than one trial to develop full accuracy."

While U.S. and Russian negotiators got Syrian President Bashar Assad to allow in a trickle of aid, U.S. Ambassador to the United Nations Samantha Power said Wednesday the Syrian government continues to strategically starve people in contested areas, CBS News foreign affairs correspondent Margaret Brennan reported.

Get Breaking News Delivered to Your Inbox

"While we welcome the latest deliveries of aid to besieged areas in Syria, the convoys are just not enough," Power said. "Trucks carrying aid have been idling for months -- if not years -- to reach people in need. And the fact that the Syrian government deigned to let convoys in only underscores that the Syrian government is playing God, deciding who they try to starve and who, for now, they don't."

Secretary of State John Kerry and his Russian counterpart, Foreign Minister Sergey Lavrov,spoke by phone Wednesday to discuss issues connected with the proposed upcoming cease-fire in Syria.

A Russian Foreign Ministry statement said the two top diplomats "continued discussion of the modalities of this process, demanding close coordination of efforts between our countries, including in the military sphere."

The statement says the two stressed the importance of "renewing the intra-Syrian talks about" the situation in the war-ravaged country and ways to resolve five years of violence that has killed more than 250,000 people and displaced another 11 million from their homes.