Nakatani supported Koichi Kato and Taku Yamasaki's no-confidence motion against Prime Minister Yoshiro Mori in 2000, and was appointed to head the Japan Defense Agency under Prime Minister Junichiro Koizumi in the following year.
In a joint letter initiated by Norbert Röttgen and Anthony Gonzalez ahead of the 47th G7 summit in 2021, Nakatani joined some 70 legislators from Europe and the US in calling upon their leaders to take a tough stance on China and to "avoid becoming dependent" on the country for technology including artificial intelligence and 5G.[5]
In December 2025, Nakatani announced his support for a constitutional amendment that would recognize same-sex marriage.[6]