The scope of human security so defined fitted well with objectives outlined in the UN’s Millennium Development Goals (MDGs). Set forth at the 2000 Millennium Summit, these MDGs are inter alia: eradicate poverty and hunger, achieve universal primary education, promote gender equity and empower women, reduce child mortality, improve maternal health, arrest the spread of HIV/AIDS, malaria, and other diseases, promote environmental sustainability, and develop a global partnership for development. Indicative of the careful structuring of the UN’s message, these goals were grouped for rhetorical effect by Secretary-General Kofi Annan (1996–2006) to resonate with the ideals of Woodrow Wilson and Franklin D. Roosevelt.
You're splitting the bolded part in a slightly incorrect way, which is what's confusing you. The way it should be considered is
The scope of human security so defined
fitted well with objectives
"The scope of human security so defined" could be said another way as "As it was defined, the scope of human security..." and the next part, "fitted well with objectives" just tells you that the definition of the scope was a good fit for the objectives the UN had.
This sentence would perhaps have been clearer if the author had included commas:
The scope of human security, so defined, fitted well with objectives etc.