The United States on Saturday deplored growing violence by the Democratic Republic Congo’s M23 rebels, saying the group’s backers in Rwanda must remove sophisticated ground-to-air missiles that are threatening lives in the country’s east.

Fighting has flared in recent days around the town of Sake, 20 kilometers from Goma, between M23 rebels and Congolese government forces.

“The United States strongly condemns the worsening violence in the eastern Democratic Republic of Congo (DRC) caused by the actions of the Rwanda-backed, U.S.- and U.N.-sanctioned M23 armed group, including its recent incursions into the town of Sake,” State Department spokesperson Matthew Miller said in a statement.

“This escalation has increased the risk to millions of people … We call on M23 to immediately cease hostilities and withdraw from its current positions around Sake and Goma,” Miller said.

Washington “condemns” Rwandan support for M23 and calls on Kigali “to immediately withdraw all Rwanda Defense Force personnel from the DRC and remove its surface-to-air missile systems, which threaten the lives of civilians, U.N. and other regional peacekeepers, humanitarian actors, and commercial flights in eastern DRC,” Miller said.

Dozens of soldiers and civilians have reportedly been killed or wounded in the fighting over the last 10 days.

The latest clashes have pushed tens of thousands of civilians to flee towards Goma, which stands between Lake Kivu and the Rwandan border and is practically cut off from the country’s interior.

The DRC, the United Nations and Western countries say Rwanda is supporting the rebels in a bid to control vast mineral resources, an allegation Kigali denies.

U.N. forces have been in the DRC for nearly 25 years but stand accused of failing to protect civilians from armed groups.