One of the things that i liked about Babylon 5 is that Earth became a bad guy under President Clark.
A planet sized North Korea complete with the propaganda and anti alien isolationist elements. Political opposition figures are arrested, tortured, made to confess and sent to prison. Human Colonies that opposed the Martial Law decree by President Clark are bombed and blockaded untill they surrendered.
It took an alliance of humans from Mars, Babylon 5 and other human colonies, renegade Earth Military personnel and their alien allies to bring down President Clark.
The scenes of earth vessels fighting earth vessels in episodes like Point of No Return
and Severed Dreams