In 2019, Harry J. Kazianis participated in an American simulation of a war between Russia and the U.S.-led North Atlantic Treaty Organization.

The conflict followed fighting in Ukraine.

The result: one billion people die in a nuclear war.

"And if we aren’t careful," Kazianis wrote in a recent article, "what happened in a simulation could happen if a NATO-Russia war erupts over Ukraine."

Kazianis is the director of defence studies at the Center for the National Interest, a think tank based in Washington DC.

Recalling the experience in an article on The Federalist, an online publication, the defence expert the mock-up was conducted by a “group of past and present senior U.S. government officials from both sides of the aisle”.

The exercise was called the “NATO-Russia War of 2019”.

“The scenario the group decided to test back in late 2019 was similar to today: Russia decided to invade Ukraine under the excuse that it is must defend Russian-speaking peoples that are being ‘oppressed’ by Ukraine’s fascist government,” Kazianis wrote in his March 4, 2022 piece.

In the simulation, Ukraine does “not give up so easily, just like in real life today”.

Then “things take a turn for the worst”.

“A Russian ballistic missile’s guidance system fails and crash-lands into NATO member Poland, killing 34 civilians as it tragically lands into a populated village along the Polish-Ukraine border,” Kazianis recalled about one scenario in the simulation.

More bad things happen, and a NATO move “surprises everyone”.

“The alliance decides to set up a limited no-fly zone around the Ukrainian city of Lviv to protect innocent civilians and refugees that are trapped and have nowhere to go,” Kazianis wrote.

Russian President Vladimir Putin “gets a sense that NATO is destined to intervene on Ukraine’s side”.

“Before NATO can impose its no-fly zone, Putin orders strikes on any remaining airfields and military assets around Lviv,” Kazianis related.

Putin also orders a “massive cyber attack on the Baltic states’ military infrastructure, thinking that NATO will use the Baltics to stage an invasion of Russia”.

“This ends up being the last straw for NATO, which then decides direct intervention in Ukraine is necessary to push back against Russian aggression,” Kazianis wrote.

But before that decision was announced, “Russian intelligence sees missile and troop movements that indicate an impending NATO attack and decide to strike first — with tactical nuclear weapons”.

“NATO decides to respond in kind,” Kazianis wrote.

Russia hits European cities with nuclear weapons, drawing retaliation from NATO and the U.S.

“What is left is nothing short of an apocalypse, with what we estimate is billion people dead,” Kazianis wrote about the result of the 2019 war simulation.

Putin announced what he called a “special military operation” in Ukraine on February 24.

Three days later on February 27, the Russian leader put his country’s nuclear forces on high alert, saying NATO officials have made “aggressive statements”.

On Thursday (March 10), Russian Foreign Minister Sergei Lavrov said that he does not believe that the conflict in Ukraine would lead to a nuclear war.

Nine countries in the world possess nuclear weapons.

The Federation of American Scientists says online that these countries “possessed roughly 12,700 warheads as of early-2022”.

“Approximately 90 percent of all nuclear warheads are owned by Russia and the United States, who each have around 4,000 warheads in their military stockpiles; no other nuclear-armed state sees a need for more than a few hundred nuclear weapons for national security,” the FAS notes.