The Economist explains

What is the Collective Security Treaty Organisation?

The Russian-led alliance is flexing its muscles in Kazakhstan

This handout image grab taken and released by the Russian Defence Ministry on January 6, 2021 shows Russian paratroopers boarding a military cargo plane to depart to Kazakhstan as a peacekeeping force at the Chkalovsky airport, outside Moscow. - A Moscow-led military alliance dispatched troops to help quell mounting unrest in Kazakhstan as police said dozens were killed trying to storm government buildings. Long seen as one the most stable of the ex-Soviet republics of Central Asia, energy-rich Kazakhstan is facing its biggest crisis in decades after days of protests over rising fuel prices escalated into widespread unrest. (Photo by Handout / Russian Defence Ministry / AFP) / RESTRICTED TO EDITORIAL USE - MANDATORY CREDIT "AFP PHOTO / Russian Defence Ministry " - NO MARKETING - NO ADVERTISING CAMPAIGNS - DISTRIBUTED AS A SERVICE TO CLIENTS (Photo by HANDOUT/Russian Defence Ministry/AFP via Getty Images)

WHEN PROTESTS in Kazakhstan, an oil-rich country of 19m people, erupted in mass unrest in the opening days of the new year, Kassym-Zhomart Tokayev, the country’s president, knew who to call. Early on January 6th he picked up the phone to the Collective Security Treaty Organisation (CSTO). Within hours, Russian paratroopers and Belarusian special forces were boarding planes for Almaty, ready to help Mr Tokayev control the uprising. What is the CSTO?

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