Why wasnt the mexican american war justified.

Three main reasons America was unjustified in going into war with Mexico were that President James k. Polk provoked it, America's robbery of Mexico's land and the expansion of slavery. ... That is why America was unjustified to go into war with Mexico.

The league of nations was found in 1919 to keep peace after world war l.but it failed to prevent world war ll in 1939,so in 1945 the nations of the world set up a new organization,the united state (un).since then, the un has encouraged international cooperation and worked to resolve conflict