US soldiers participated in the DEFENDER 24 exercise in the Czech Republic intended to strengthen the NATO alliance.Lukas Kabon/Getty ImagesTrump has threatened to quit NATO. A wargame examined the possible ramifications.The US player abandoned Ukraine and ceased NATO participation, triggering crisis in Europe. The game's designer says it showed Trump "doesn't need to leave NATO to ruin it."If Donald Trump wins a second term in the White House in November, NATO may fall apart, a recent wargame found.As a presidential candidate, Trump has threatened to quit NATO unless European allies contribute more, and should he carry it out Europe may decide to go it alone on defense, the game suggests.