The tropical typhoon - the strongest on Earth so far this year - was producing sustained winds of 173 mph (278 kph) on Monday as it neared the islands of Rota, Tinian and Saipan, according to the Joint Typhoon Warning Center.
While it's expected to weaken slightly over the next few days, Sinlaku should cross near the islands as a Category 4 or 5 typhoon.
About 50,000 people live on the three islands, with most on Saipan, known for its laid-back resorts, snorkeling, and golf as well as the capital of the Northern Mariana Islands.
Saipan was the site of one of World War II's bloodiest battles in the Pacific, in which more than 50,000 Japanese and American soldiers and local civilians died.
In Guam, where Typhoon Mawar knocked out power for days in 2023, U.S. military officials warned personnel to prepare for the storm and shelter in place. The military controls about one-third of the land on the island, a critical hub for U.S. forces in the Pacific.