President Joe Biden is set to meet with two of America's closest allies to announce that Australia will purchase US-manufactured, nuclear-powered attack submarines to modernize its fleet, amid growing concerns about China's influence in the Indo-Pacific region. Biden is traveling on Monday to San Diego, where he will meet Australian Prime Minister Anthony Albanese and UK Prime Minister Rishi Sunak for talks on the 18-month-old nuclear partnership known by the acronym AUKUS.