Researchers will be allowed to access the files beginning Sept. 18. They cover the period from Feb. 6, 1922, to Feb 10, 1939.
In 2003, the Vatican began making available to scholars millions of Vatican documents from the years leading up to World War II, releasing them ahead of schedule at the request of Pope John Paul II.
For years, the Vatican has struggled to defend Pius' successor against claims he didn't do enough to save Jews from the Holocaust, the AP reports.
The United States has imposed new sanctions against the Nord Stream 2 gas pipeline project, which still remains under construction