"precipitate war" is a correct and usable phrase in written English.
It is used to describe a situation in which a war is started suddenly and without warning, typically due to a single event that acts as a catalyst, such as a sudden attack. For example: The assassination of the country's leader precipitated war between the two neighboring nations.
That agreement precipitated war between Poland and Russia.
Resenting the threat of the Duke of Alba's Spanish army in the Netherlands, Cecil nearly precipitated war in December 1568 by instigating the seizure of ships carrying bullion to Alba, who retaliated by closing Antwerp to English trade.
Uzun Ḥasan's support of the Karamanids, however, precipitated war (1472) with the Ottomans (August 1473), who decisively defeated the Ak Koyunlu at the Battle of Terjan and thus emerged supreme in Anatolia.
Just two days before Frederick died, a joint constitution for Denmark and the Duchy of Schleswig was ratified by the Rigsråd, a decision that precipitated war with the German powers in 1864.
In April of that year, The New York Times reported that a West Side Republican Club member identified as Bertha Welby had given an address in the hall praising President William McKinley, a Republican, for "the cool and rational way in which he has avoided precipitating war until the plans of the country were thoroughly and well advanced".
An expedition under Sir James Gambier in July 1807 had captured most of the Danish Navy at the Battle of Copenhagen, in response to fears that it might fall into Napoleon's hands, but precipitating war with the Danes.
Democracy is now spreading at the expense of liberty by feeding ethnic hatreds, precipitating wars or undermining the institutions of liberty.
The plots, he said, were intended to precipitate civil war in Afghanistan.
The stakes are enormous: done right, our military drawdown will motivate Afghans and their neighbors to negotiate seriously with each other about their future; done wrong, it could precipitate another war.
But anarcho-syndicalists, hoping to sabotage the conference and precipitate World War II, sneak into the President's suite and depress the "Alarm" button so that it will not go off.
