M23 rebels, reportedly backed by Rwanda, claimed control of Goma, the largest city in eastern Congo, early Monday. This development comes as the Congolese government cut diplomatic ties with Rwanda, with Congolese spokesman Patrick Muyaya calling the situation a "declaration of war.

Congolese rebels and allied Rwandan forces entered the outskirts of Goma on Sunday and the airport in the key eastern city was no longer in use, the top U.N. official in the country said. Thousands fled the fighting that also killed at least 13 peacekeepers.