In 1959, it merged with several other trading companies and changed its name to Mitsui & Co., Ltd.[2] During Japan's period of rapid postwar economic growth, the firm was a key player in several major natural resources projects.

Some analysts had thought BP would realize a larger settlement from MOEX, but there was also relief to have a first step toward resolving the multiple claims.

The Japanese trading giant has maintained its stake in the Sakhalin-2 liquefied natural gas (LNG) project, citing the need to ensure energy supplies to Japan.

Mitsui holds a combined 22.5% share in the project, which remains operational under Russian control following the Kremlin's restructuring.

Critics argue that Mitsui's continued involvement undermines the global effort to isolate Russia economically, indirectly supporting a regime responsible for ongoing war crimes and atrocities in Ukraine.