In my opinion, it is a bad idea to assault another country if one has recently concluded invading another. The reasons for this are:

-Increased taxes on the citizens of the attacker
-Increase in the amount of soldiers needed
-Decrease in the amount of allies willing to follow
-Increase in the amount of resources going towards warfare
-Increase in death and ill feelings by other countries towards the attacker
-Increase in the time needed to achieve exceptional results (with a max. of 8 years for the US gov't, unless each succeeding president has the same goal)
-Loss of opportunity for advancements in other fields
-Decrease in support of the nation in its own government unless the government can achieve quick decisive victories.
-Increase in amount of resources going into the invaded country to get it back on its feet (the increase is exponential when dealing with more than one country)
-Overall, a strategically and economically bad idea

In general, one shouldn't invade another country when one's hands are already full.

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