Some info from Independence Day : Crucible
SPOILERS FOR THE BOOK
Immediately after the War the Mediterranean Sea was a wreck- awash with craft ranging from aircraft carriers to manmade rafts. Many people were dying there each day-presumably fleeing from all directions since the CD's had struck heavily in the general area.
Since most of the great cities of Africa were on or near the sea the interior of the continent was not nearly as effected by the invasion-at least at first.
The CD in Congo went down near Little Babale.
(as established in Independence Day: War in the Desert) The aliens in Africa, Saudi Arabia and likely elsewhere spread away from their ships foraging for food and breeding -planting cocoons in tree stands and marshes and spreading their own insidious vegetation. The cocoons contained fetal aliens which absorbed vegetation around them for nourishment.
In June 1997 David Levinson attends a meeting at the new White House which is still being rebuilt . He meets the new Vice President Stephen Bell-who was also convinced to run as Grey's VP in 2000.
President Whitmore tells David that with the economy in a shambles there are no plans to rebuild New York, Los Angeles ,Houston or any of the other lost cities. So many people were lost its easier to build a new life or continue where there is existing infrastructure. Washington- and its monuments- however have to be re-built for the unity and stability of the country.
Levinson argues that there needs to be a clearinghouse for the alien technology -for military and civilian use -, a beefed up SETI and a moon base that is an international effort. VP Bell says that the US government most be involved in only military applications of alien tech and the private sector can handle things like "zero-grav coffee makers". Whitmore agrees with David and tells him of his idea for the Earth Space Defense initiative -which will be international.
David also presses for access to the nearly intact CD in Congo. Whitmore advises that they have refused all outside assistance and in the interest of international unity there will be no invasion or covert action in the area. They will have to make do with the nearly 30 accessible CD wrecks-which presumably the one in Sydney is not since it crashed in water
In February 1999 President Whitmore and David Levinson attend a meeting in New Beijing where they meet President Qian who was a junior member of the Politburo before the Fourth but as in the US the vast majority of Chinese leaders had been wiped out in the attacks and replaced by younger, less experienced people.
Immediately after the War of 96 Tibet had attempted a revolt against Chinese troops there while the Chinese government was pre-occupied with the ground war with the aliens. This is hanging up implementation of China's role in the Naples ( perhaps a mistake since Naples was hit in Wave 2 ? ) agreement towards global unity.
The Chinese president stuns Whitmore by saying in the interest of human unity China is willing to make some compromises regarding its territories-including Tibet and Taiwan. They also come to agreement regarding their respective roles in the ESD- the US will focus on building fighters and the Chinese job will be heavy lifters-tugs, transports, pre fab housing-the Moon base essentially.
EDIT- the book hasn't said it directly but one gets the impression that humans killing humans has become very taboo in this world.