As a final, intensive year of campaigning begins ahead of the 2020 presidential election, the Marine Corps has issued a new message to troops making clear what's off-limits to them in terms of political activity -- particularly on social media. The message, released this month, reiterates past guidance: Marines can vote and verbally express political opinions, but cannot use their uniform to suggest military endorsement. But it expands on historically grey areas that have gotten troops into trouble. Read more on Military.com.