By setting up fake accounts pretending to be Americans. By stealing the identities of real US citizens and using their real social security numbers and birthdates . By setting up social media posts, onlines and rallies inside the United States to promulgate unrest and hurt Hillary Clinton, Ted Cruz, Marco Rubio specifically and support doofus don and for some reason Bernie Sanders. They were very busy bees covering multiple things. Very efficient. Very proficient. Very smart. Much smarter than the folks who fell for it. SIGH.