The U.S., U.K. and Australia have announced a trilateral agreement to develop a next-generation submarine, SSN-AUKUS, based on the U.K.'s design and incorporating U.S. technologies. The submarine is part of a larger effort to modernize Australia's fleet and counter China's growing influence in the region. China has criticized the agreement, but the U.S., U.K. and Australia are sending a clear message that they will continue to work together to ensure a secure and prosperous future for the Indo-Pacific region.