Fifteen months of devastating war in Gaza could come to a halt as soon as Sunday, with Israel’s government poised to approve a ceasefire and hostage release deal with Hamas.  Though the exact details of the agreement have not been publicly released, the contours follow President Biden’s May proposal, which was endorsed by the United Nations Security Council. “This is the ceasefire agreement I introduced last spring,” Biden said in remarks Wednesday, announcing the deal. There were some final hang-ups this week, over which Palestinian prisoners would be released from Israel’s jails, and where they will be sent, as well as the ongoing presence of Israeli troops in the Philadelphi Corridor, which runs along the entire Gaza-Eqypt border.  However, Israel’s security Cabinet approved the deal Friday, and it’s set for prompt approval from the full Cabinet, meaning hostages could start walking free by Sunday, just ahead of President-elect Trump’s inauguration.  Here’s what we know about how the ceasefire will work The agreement is a three-phase deal that begins with a halt in fighting, the release of hostages held by Hamas and Palestinian prisoners in Israeli jails, along with a scale-up of humanitarian aid, and withdrawal of some Israeli military forces from the Gaza Strip. This period is supposed to last six weeks, with negotiations for the second phase of the deal beginning on the 16th day of the ceasefire, according to a detailed framework provided to The Hill by Hamas. If an agreement to begin the second phase of the deal is not achieved by the end of the initial six-week ceasefire, Biden said that as long as Israeli and Hamas officials are committed to continuing the talks, the ceasefire could continue indefinitely.  During this time, humanitarian aid into the Gaza Strip is expected to surge, as long as the truce holds, allowing the rehabilitation of civilian infrastructure, including electricity, water, sanitation, telecommunications and roads. Supplies for civil defense, debris removal, and rubble clearance will also be delivered. At least 60,000 temporary housing units and 200,000 tents are listed as required for people who lost their homes. The transition between the first and second phase of the deal is expected to be the most fraught period, and will be overseen by the incoming Trump administration, which was also involved in the push for a deal in Biden’s final days in the White House.  Israeli officials will be on guard against Hamas extending talks in bad faith, using the time to reconstitute its military. And at any point, Israel could restart military operations if it sees a renewed threat from the U.S.-designated terrorist group.  The U.S., Egypt and Qatar are expected to mediate between Israel and Hamas during the transition between the first and second phase. To start the second phase, Israel and Hamas must agree on a permanent ceasefire.  What happens in the second and third phases If a second phase is reached, more hostages held by Hamas — to include Israeli soldiers — will be released, and Israel will release Palestinian prisoners in Israeli jails. The second phase is expected to last 42 days. The May text does not indicate how a transition from Phase 2 to Phase 3 will be accomplished. The third phase will see Hamas release the bodies and remains of deceased hostages; the further release of Palestinian prisoners from Israeli jails, and a major reconstruction effort of the Gaza Strip, to take place over a period of three to five years. Gaza’s border crossings are expected to be open to facilitate the movement of people and goods.