On 6 December, INFN and the Deutsches Zentrum für Astrophysik (DZA) signed a letter of intent to launch a collaboration aimed at strengthening research and technology development activities for the Einstein Telescope (ET) project. The agreement was signed by INFN President Antonio Zoccoli and DZA Director Günther Hasinger. The collaboration between the two entities will cover the characterisation of the candidate site of Sos Enattos in Sardinia and the German site in Lusatia, whose candidacy to host ET was recently proposed to the scientific community. In addition, the agreement envisages the implementation of joint research and development projects, particularly in the design phase of the experiment, in which both detector configuration hypotheses will be studied, either the one involving the construction of two L-shaped instruments in Sardinia and Lusatia, and the one involving a single triangular-shaped detector in one of the two regions. Finally, the two institutes will foster the exchange of researchers between the two countries and organise joint seminars and workshops, as well as invite other European institutes to join the collaboration agreement.