The US Navy Pacific Fleet orders all forward-deployed and some locally deployed nuclear submarines to the Western Pacific to perform "emergency response operations." Participants in this operation include all rapid attack nuclear submarines stationed in Guam, and some Pearl Harbor and San Diego, with a total of more than 7 ships.
https://twitter.com/BoDiplo/status/1263133077645209601
How U.S. Navy Submarines Are Pushing Back Against China in the South China Sea
https://nationalinterest.org/blog/buzz/how-us-navy-submarines-are-pushing-back-against-china-south-china-sea-155941