From the aforementioned NSSM-200:
"Whatever may be done to guard against interruptions of supply and to develop domestic alternatives, the U.S. economy will require large and increasing amounts of minerals from abroad, especially from less developed countries. That fact gives the U.S. enhanced interest in the political, economic, and social stability of the supplying countries. Wherever a lessening of population pressures through reduced birth rates can increase the prospects for such stability, population policy becomes relevant to resource supplies and to the economic interests of the United States."
Good Cite.
It seems to me that it is even more urgent when you factor in national security. I completely agree with the assessment that populations controls can help maintain political, economic, and social stability. All are important factors in our overall national security policy. As I mentioend before, uncontrolled population growth will result in instability that will spill over into neighboring nations or our allies.
By helping these nations to control their population growth through family planning, we are helping to ensure stability. And with the proliferation of weapons of mass destruction, maintaining stability has become more important than ever before.