DAKAR, Senegal — Rwanda-backed rebels appeared to be heading toward a third major city in eastern Congo, residents said Tuesday, as international pressure rose over the M23's expansion in a mineral-rich region that’s critical for global technology.

On February 16th soldiers from M 23 marched single-file through the streets of Bukavu, eastern Congo’s second-largest city. The beleaguered remains of the Congolese army had retreated without a fight. Rebel fighters toting grenade-launchers and machine-guns took triumphant selfies in the city’s main square.

The United Nations Security Council condemned Rwanda for backing a rebellion in eastern Democratic Republic of Congo and ordered its troops to withdraw from the country.