Complex sentence: After Endean gives Shannon $5 million for expenses, Shannon contacts his mercenary cohorts from Central America (3 of whom join him; 1 does not) and illegally procures Uzi submachine guns, ammunition, rocket launchers, mines, and other weapons from arms dealers.
Split into simpler sentences: After Endean gives Shannon $5 million for expenses, Shannon contacts his mercenary cohorts from Central America (3 of whom join him; 1 does not). The group illegally procures Uzi submachine guns, ammunition, rocket launchers, mines, and other weapons from arms dealers.