Captain Halima Ascot is an officer of the United Nations Space Command Navy. She was the captain of the Razor-class prowler UNSC Starry Night and the commander of Task Force Yama, formed to execute Operation: SILENT STORM in early 2526.

On March 8, 2526, Captain Halima Ascot was summoned by Vice Admiral Preston Cole aboard the UNSC Vanishing Point, along with John-117, Colonel Marmon Crowther, Staff Sergeant Avery Johnson, and Dr. Catherine Halsey. Here, they were briefed on Operation: SILENT STORM, which was the UNSC's plan to slow down the Covenant's advance by boarding their vessels and destroying them from the inside, much like the Spartans had just done to the Radiant Arrow, but purposefully. For the duration of the operation, Ascot was given command of Task Force Yama, a splinter group of Cole's Battle Group X-Ray that would be composed of Sahara-class heavy prowlers, Eclipse-class prowlers, Razor-class prowlers, and the Vanishing Point itself. Task Force Yama would act as transport and support for the Spartans and Crowther's elite 21st Space Assault Battalion, called the Black Daggers.

With the Covenant currently glassing the colony of Etalan, it was theorized that they would move on to Biko next. The outer colony was an agriculture world, with resource-rich moons and a handful of shipyards. All of which made it a valuable forward base for the UNSC, something that the Covenant certainly would not allow. As such, Task Force Yama would travel to Biko and wait for the Covenant to arrive, using an abandoned ice quarry on its moon of Seoba as a base. With the operation underway, Captain Ascot took the task force into slipspace, en route to the Kolaqoa system.