Why does the State Department seem to often want to force a country to be unified as opposed to segmented.
We see this nearly everywhere.
There was terrible reluctance to allow Iraq to split into three countries. There is reluctance to let Afghanistan split into 5 countries. Currently we are opposed to seeing the Ukraine split into three countries or Syria into 6 countries.
Where does this reluctance come from?
We have a long history. Almost our entire 200+ years of existence, of forcing political subunits into forming a single country. We have strongly opposed most fragmentation. Whether it is French, Spanish or Canadian. The eighteenth century foreign policy was heavily focused on the unification of countries such as Germany and Italy.
On the otherhand we opposed the expansion of Russia into the USSR and we opposed the expansion of Japan into its Greater East Asian Sphere of Influence,
So what are we doing, what is our policy?
Our policy is to put together small units that would not be homogeneous into a larger nation. Homogeneity usually means 'tyrannical' to us. Large nation states that are diverse are inherently less able to be aggressive.
More complex, diverse, nations present less threat to their neighbors than homogeneous nations largely because they have to appease the multiple political forces within their geographic domain. Think Lebanon over the past few centuries.
In summary we encourage and support political subunits and ethnic groups to form larger nations or to remain as larger nations because we believe that larger diverse nations are simultaneously more stable, in international terms, because they are domestically much more complex and because complex nations are less likely to attack their neighbors.
We did not feel this way about the USSR for the Russians or the East Asians Sphere for the Japanese because they seem to be on an expansionist tear to rule the world rather than to create a complex domestic political entity. We tolerated the breakup of Yugoslavia and Czechoslovakia to provide a buffer against Russian expansion.