The Israel Defense Forces has announced that it has opened a new crossing to bring humanitarian aid into the famine-stricken Gaza.

The military announced in a Sunday press release the opening of the Western Erez crossing between Israel and northern Gaza in coordination with the U.S.

According to the military, the new crossing is located west of the Erez crossing, closer to the seashore. The crossing was constructed by the Israeli military "as part of the effort to increase routes for aid to Gaza, particularly to the North of the strip."

Earlier Sunday, IDF said it launched a large-scale operation in the area of Jabaliya in the North, while intensifying its military operations in the Eastern portion of Rafah and the Gaza side of the Rafah crossing. It said that it had called on the civilian population to evacuate from Jabaliya to shelters in the west part of Gaza City.

-ABC News' Dragana Jovanovic

In a phone call Sunday with his Israeli counterpart, White House National Security Advisor Jake Sullivan expressed an "ironclad U.S. commitment" to Israel but also voiced the Biden administration's concerns about Israel's major military operations in Gaza, according to the White House.

During the call with Israeli National Security Advisor Tzachi Hanegbi, Sullivan reiterated President Joe Biden's "longstanding concerns over the potential for a major military ground operation into Rafah, where over one million people have taken shelter," according to a readout of the call that was released by the White House.

"He [Sullivan] discussed alternative courses of action to ensure the defeat of Hamas everywhere in Gaza," the readout said. "Mr. Hanegbi confirmed that Israel is taking U.S. concerns into account."

The White House said Sullivan also expressed condolences on Israel's Memorial Day, the first since Hamas' surprise Oct. 7 attacks on Israel. The Hamas attack killed 1,200 people, most of them civilians, according to Israel's Prime Minister's Office.

Sullivan and Hanegbi also reviewed discussions by officials on both sides of the war about alternatives for a Rafah invasion and agreed to plan an in-person meeting soon, according to the White House.

-ABC News' Michelle Stoddart

More than 300,000 people have fled Rafah in the week since Israel issued a partial evacuation order, the United Nations agency operating in Gaza said on Sunday.

The U.N. Agency for Palestine Refugees called the evacuation "forced and inhumane."

"There is nowhere safe to go," the agency said on social media, repeating the phrase three times for emphasis.

The Israeli military late Saturday called again for civilians to evacuate from much of the eastern part of the city, which is in southern Gaza.

Israel Defense Forces entered Rafah last week, in what they called a "precise" operation ahead of potential invasion.

"Prior to our operations we urge civilians to temporarily move towards humanitarian areas and move away from the crossfire that Hamas puts them in," the Israel Defense Forces said on a post on Telegram. "Our war is against Hamas, not against the people of Gaza."

-ABC News' Dragana Jovanovic and Kevin Shalvey

An independent, self-formed task force of former State Department officials and international law experts say the U.S. "shirked" its legal obligations with Friday's National Security Memorandum-mandated report that examined Israel's use of U.S.-supplied arms.

"The Administration must come to terms with the fact that what it faces in its lethal military assistance to Israel's operations in Gaza - and beyond - is not a policy problem: it is a legal problem," the officials said Friday, adding, "The Administration’s report is at best incomplete, and at worst intentionally misleading in defense of acts and behaviors that likely violate international humanitarian law and may amount to war crimes. Once again, the Biden Administration has stared the facts in the face - and then pulled the curtains shut."

More than 34,000 Palestinians have died, including 14,000 children, the officials said, noting that "most of them [were] killed by U.S. munitions."

-ABC News' Christopher Boccia

A new report from the United States Departments of State and Defense said that given "Israel's significant reliance on U.S.-made defense articles" it is "reasonable to assess" that some have been used in instances "inconsistent" with Israel's obligation under international law.

The assessment, which came as part of a report ordered by President Joe Biden, examined the use of U.S.-supplied arms in active conflict zones, and also said that the U.S. could not compile enough evidence to prove that the country used American defense articles in violation of international humanitarian law.

"We do not have complete information to verify whether US defense articles covered under NSM-20 were specifically used in actions that have been alleged as violations of IHL (international humanitarian law) or international human rights law during the period of the report," the document says. "The nature of the conflict in Gaza makes it difficult to address or reach conclusive findings on individual incidents."

While the report said the Israeli government has "the knowledge, experience, and tools" to implement "best practices for mitigating civilian harm," the high number of civilian casualties "raise substantial questions about whether the IDF is using them effectively in all cases."

Additionally, the report noted that Israel did not cooperate with U.S. efforts to ramp up humanitarian aid and distribution in Gaza during the initial months of the conflict, but that officials have observed improvements.

-ABC News' Shannon Crawford and Anne Flaherty