The December 2021 edition of the IRMO Brief, authored by Krševan Antun Dujmović, deals with the security pact between Australia, the United Kingdom and the United States of America (AUKUS). The pact was signed on September 15th 2021 in order to strengthen the security and defense cooperation between the three countries in the Indo-Pacific region. The AUKUS pact provoked both positive and negative reactions, with China being its greatest opponent. Since the pact involves the transfer of nuclear-powered submarines from the USA and the UK to the Royal Australian Navy, China is concerned that AUKUS is directed against its interests in Southeast Asia. On the other hand, the countries in the region like Japan, India, Singapore and the Philippines have welcomed AUKUS as a mean to deter China. The author also analyses in which way will AUKUS affect transatlantic relations, as some EU members fear AUKUS will alienate the US from Europe.