"direct war" is correct and usable in written English.
You could use it to describe an open armed conflict between two or more parties. For example: The two nations had been in a standoff for months before resorting to direct war.
But the military is in no danger of running out of money for combat since $70 billion in direct war spending was approved last month.
In response to an ongoing fight that could spill out beyond the Arabian peninsula, Saudi Arabia has entered into direct war with the Houthi rebels in northern Yemen.
And Ahmad Shohani, a member of parliament, has said that Syria's government should not expect Iran to get into a direct war with the West in the case of an American strike.
At the same time, Japanese gangs who were fighting over black market turf with the Koreans began reviving the old yakuza structure, and incorporated many Korean-Japanese into their ranks: rather than wage direct war, they began a successful policy of assimilation.
Figure 2. Direct War Related Deaths in Pakistan since 2004.
Direct war damage sustained by the city was estimated at a total of US$1.3 billion.
As the Democratic lieutenant governor when Gov. Herbert H. Lehman resigned 29 days before his term expired, to direct war-relief efforts in Europe, Mr. Polletti, 39, moved in -- becoming the nation's first Italian-American governor.
India has now fought three direct wars with Pakistan, two of them over Kashmir.
Direct War-Related Deaths in Afghanistan since 2001.
Defense Secretary Donald H. Rumsfeld directed war strategy in Iraq.
Marianne Elliott, who co-directed War Horse with Tom Morris, is surely a contender.
