August 1916
During the WW1 Romania was an allied country.
In the WW1 Romania was an ally of Western countries.
Romania entered in the WW2 (Great Romania was after WW1) because Soviet Union occupied Basarabia and Northern Bukowina.
Between 1914-1916 Romania was neutral.In august 1916 Romania joins the Triple Entente and mobilizes against Austro-Hungary. = =
Romania was forced by the Western European countries.
Romania was against Germany and Austro-Hungary.
Romania joined NATO on 29 March 2004.
the united states joined in 1917, ww1 started in 1914.!!
They did join WW1...
2007.
The answer is impossible today; in the future !
the usa joined it