This handout photo shows Israeli forces operating on the Palestinian side of the Rafah border crossing between Gaza and Egypt in the southern Gaza Strip on Tuesday. AFP

Israeli troops seized control of Gaza’s vital Rafah border crossing on Tuesday in what the White House described as a limited operation, as fears mount of a full-scale invasion of the southern city and talks with Hamas over a cease-fire and hostage release remain on a knife’s edge.

The UN warned of a potential collapse of the flow of aid to Palestinians from the closure the Rafah crossing from Egypt and the other main crossing into Gaza, Kerem Shalom, from Israel, at a time when UN officials say northern Gaza is experiencing "full-blown famine.”

The Israeli foray overnight came after hours of whiplash in the now 7-month-old Israel-Hamas war, with the group saying Monday it accepted a cease-fire proposal that Israel insisted fell short of its own core demands.

The high-stakes diplomatic moves and military brinkmanship left a glimmer of hope alive for a deal to bring at least a pause in the war, which has killed more than 34,700 Palestinians, according to local health officials, and has devastated the Gaza Strip.

The Rafah and Kerem Shalom crossings are critical entry points for food, medicine and other supplies for Gaza’s 2.3 million people. They have been closed for at least two days, though the smaller Erez crossing between Israel and northern Gaza remains open.

Palestinians with dual citizenship walk at the Rafah border crossing with Egypt in Rafah. File/Reuters

By capturing the Rafah crossing, Israel gained full control over the entry and exit of people and goods for the first time since it withdrew soldiers and settlers from Gaza in 2005, though it has long maintained a blockade of the coastal enclave in cooperation with Egypt.

Israeli Prime Minister Benjamin Netanyahu called the capture of the crossing an "important step” toward dismantling Hamas' military and governing capabilities, and Defense Minister Yoav Gallant said Israel would "deepen” the Rafah operation if talks on the hostage deal failed.

Osama Hamdan, a Hamas official based in Beirut, said the group would not respond to military pressure or threats and would not accept any "occupying force” at the Rafah crossing.

White House National Security Council spokesman John Kirby said the operation along the Gaza-Egypt border in eastern Rafah was not a full-on Israeli invasion of the city that President Joe Biden has repeatedly warned against on humanitarian grounds. Kirby said Israel described it as "an operation of limited scale and duration” aimed at cutting off Hamas arms smuggling.

Kirby also expressed optimism about the negotiations, saying Israel and Hamas "should be able to close the remaining gaps” to complete an agreement. He said CIA chief William Burns will attend further talks in Cairo with representatives from Israel, Egypt and Qatar. Hamas also sent a delegation to Cairo, which will meet separately with the Arab mediators.

"Everybody is coming to the table,” Kirby said.

Associated Press