A convoy of trucks loaded with humanitarian supplies such as food, water and medicines began entering Gaza from Egypt via the Rafah crossing on Saturday morning.
Twenty trucks were estimated to have crossed from the Egyptian border, carrying supplies that the UN described as "the difference between life and death for so many people in Gaza."
Humanitarian agencies, however, have said the initial aid delivery is a "drop in the ocean" and policymakers have called for the sustained delivery of essential goods to meet the needs of those living in the besieged enclave.
"The situation remains dynamic and fluid and the security environment is unpredictable," according to the U.S. embassy in Israel in a security alert to Americans, warning it could be chaotic and disorderly "should the border open."
Meanwhile, Israel's military spokesman said Saturday it plans to step up attacks on the Gaza Strip starting Saturday in preparation for the next stage of the country's war on Hamas.
Rear Adm. Daniel Hagari also repeated his call for residents of Gaza City to head south for their safety.
Two American hostages, mother and daughter Natalie and Judith Raanan, were released Friday after being held hostage by Hamas in the Gaza Strip for two weeks. President Joe Biden spoke to them, and Secretary of State Antony Blinken said a team from the U.S. Embassy will meet with them shortly.
It is two weeks since the Palestinian militant group Hamas launched its assault on Israel, killing 1,400 people and taking 200 hostage. Over 4,000 people have been killed in Gaza and more than 13,000 injured since the Israel-Hamas war began, according to Palestinian authorities.