Russian soldiers and Kremlin-backed armed forces assumed control in the Crimean peninsula and other sections of Ukraine Saturday, according to major media reports, prompting stern comments from President Obama and heightening concerns for Ukraine's sovereignty.

Here are journalists and other news sources to track on Twitter as events develop. Suggest others to follow in the comments box below.

• Shaun Walker, The Guardian, @shaunwalker7


• Mark MacKinnon, The Globe and Mail, @MarkMacKinnon


• Alexander Marquardt, ABC News, @MarquardtA

• Daniel Sandford, BBC News, @BBCDanielS

  • James Mates, ITV News, @jamesmatesitv

  • Elizabeth Palmer, CBS News, @elizapalmer

  • Lindsey Hilsum, Channel 4 News (London), @lindseyhilsum

• William Booth, Washington Post, @BoothWilliam

  • Steven Lee Myers, The New York Times, @slmmoscow

Putin informs the upper house of parliament that he will use military force in Ukraine "until the normalization of the situation" there! — Steven Lee Myers (@slmmoscow) March 1, 2014

Simon Shuster, TIME, @shustry

Ukrainian Updates, @Ukroblogger

• Christopher Miller, KyivPost, @ChristopherJM

Paul Sonne, The Wall Street Journal, @paulsonne

James Marson, The Wall Street Journal, @marson_jr

Maxim Eristavi, freelancer covering Ukraine, @MaximEristavi

Maria Daniloa, Associated Press, @mashadanilova

Max Seddon, BuzzFeed, @maxseddon

Roland Oliphant, The Telegraph, @RolandOliphant

Storyful list of journalists in Ukraine and other Ukraine sources