The United Nations on Tuesday warned that maintaining the fragile Gaza cease-fire is crucial to preventing famine and ensuring life-saving food aid reaches civilians, urging Israel to reopen all border crossings.

The U.S.-brokered truce between Israel and Hamas took effect Oct. 10, but tensions flared Sunday when Israeli forces launched deadly strikes in Gaza, citing alleged violations by Hamas.

“Sustaining the cease-fire is vital – really, it’s the only way we can save lives and push back on the famine in northern Gaza,” said Abeer Etefa, the World Food Program’s Middle East spokeswoman, speaking in Geneva.

Acknowledging the tenuous calm, she added, “We know it’s a fragile cease-fire; the most important thing is that it lasts.”

Etefa said that since the cease-fire came into force, 530 WFP trucks had crossed into Gaza, bringing in more than 6,700 tons of food – enough for close to half a million people for two weeks.