CAIRO (AP) Israeli troops seized control of Gazas 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 knifes edge.

The U.N. 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 U.N. 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 militant 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 Gazas 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.