Joe Biden's tenure as the 46th president of the United States began with his inauguration on January 20, 2021. Biden, a Democrat from Delaware who previously served as vice president for two terms under President Barack Obama, took office following his victory in the 2020 presidential election over Republican incumbent president Donald Trump. Upon his inauguration, he became the oldest president in American history, breaking the record set by Ronald Reagan. Biden entered office amid the COVID-19 pandemic, an economic crisis, and increased political polarization.

AUKUS, also styled as Aukus, is a trilateral security partnership for the Indo-Pacific region between Australia, the United Kingdom, and the United States. Announced on 15 September 2021, the partnership involves the US and the UK assisting Australia in acquiring nuclear-powered submarines. The partnership also includes cooperation on advanced cyber mechanisms, artificial intelligence and autonomy, quantum technologies, undersea capabilities, hypersonic and counter-hypersonic, electronic warfare, innovation and information sharing. The partnership will focus on military capability, distinguishing it from the Five Eyes intelligence-sharing alliance that also includes New Zealand and Canada.