defect from (something)
To leave some place, often under repressive conditions and when it is prohibited. I defected from my homeland after witnessing the atrocities carried out by the government.
defect to (something)
To leave some place, often under repressive conditions and when it is prohibited, and go to another place. I defected to this country after witnessing the atrocities being carried out in my homeland.
defect from something
to run away from something; to forsake something. Thousands of soldiers defected from the army. Roger would never think of defecting from the armed services.
defect to something
to forsake one group and take up with another. Will he defect to the other side? David defected to a small East European country.