5 Things

Russian diplomats   Russia is warning it will retaliate after more than 20 countries said they will kick out more than 100 Russian diplomats. A Kremlin spokesman said Russia would be "guided by the principle of reciprocity" in its actions. The US alone is expelling 60 diplomats and closing a consulate in Seattle, the most forceful action President Trump's ever taken against Vladimir Putin's government. The mass expulsions are being done in solidarity with the UK's recent decision to throw out almost two dozen Russian diplomats after it said the Russians were behind the poisoning of an ex-Russian double agent and his adult daughter. UK Prime Minister Theresa May said the agent and his daughter "may never" fully recover from the poisoning.

Facebook

The social media site that for years could do no wrong suddenly can't catch a break. The Federal Trade Commission is investigating Facebook's data practices as the fallout from the Cambridge Analytica data-sharing scandal continues. The FTC wants to know how data from Facebook users ended up in the hands of Donald Trump's 2016 campaign consultants. Facebook's stock also is taking a beating, and the hashtag #DeleteFacebook is still on fire. If you want to know just how much info Facebook's collected on you over the years, CNN's Sara Ashley O'Brien shows you how.

Kim Jong Un   Is Kim Jong Un in China? An official "with deep knowledge of North Korea" told CNN there's a strong possibility that the North Korean leader is in Beijing. If he's there, it's the first time he's left the country since he took power in 2011. Whispers of a possible visit took off after images of a train that belongs to Kim's family popped up online. This alleged visit comes just weeks before Kim's planned summit with South Korea's President and a potential meeting with President Trump.

2020 Census   The 2020 Census will reinstate a question about citizenship, the Commerce Department says. The Justice Department asked for its inclusion, saying it's needed to help enforce the Voting Rights Act. But critics fear it will spur a huge drop in immigrant response rates and leave a lot of people uncounted. Census data is used to determine where federal money is spent and how congressional districts are drawn, among other uses. The Census is intended to count the entire population, not just US citizens. The citizenship question was dropped from the decennial count after the 1950 census.

Linda Brown The woman at the center of the landmark Brown v. Board of Education case has died. Linda Brown passed away at 75 over the weekend in Topeka, Kansas. It was there that her father, in 1951 when she was 9, tried to enroll Brown in an all-white school near their home. When the school blocked that, her father sued, sparking the case that would end legal segregation in American schools.