UNITED NATIONS (AP) — The United States on Wednesday pledged to support a set of principles that give a green light for U.N. peacekeeping troops and police to use force to protect civilians in armed conflicts.

U.S. Ambassador Samantha Power made the announcement at a high-level U.N. meeting focusing on the responsibility to protect civilians facing violence, saying the United States was "proud" and "humbled" to be joining 28 other countries that have signed on to the Kigali Principles.

Peacekeepers from the 29 countries in missions that have a U.N. Security Council mandate to protect civilians are now authorized to take "direct military action against armed actors with clear hostile intent to harm civilians" — and their commanders can authorize force "in urgent situations" without consulting their capitals.

"The Kigali Principles are designed to make sure that civilians are not abandoned by the international community again," Power said, recalling how U.N. peacekeepers left Rwanda before the 1994 genocide and Srebrenica before the 1995 massacre.

Simon Adams, executive director of the Global Center for the Responsibility to Protect, said 10 of the 16 U.N. peacekeeping missions, including 97 percent of the 105,000 troops and police currently deployed, have Security Council mandates to protect civilians.

"However, despite the presence of sizable peacekeeping operations the United Nations continues to struggle to protect civilians from mass atrocity crimes" in the Central African Republic, Congo, Sudan and South Sudan, he said.

Power said the 29 countries that have endorsed the Kigali Principles account for more than 40,000 U.N. troops and police, well over one-third of U.N. peacekeepers. The United States is the largest financial contributor to U.N. peacekeeping operations but has very few uniformed personnel deployed in U.N. missions.

Rwanda, the Netherlands and the United States initiated the principles which were adopted at a high-level meeting in May 2015 in Kigali by the top 30 troop and police contributors to U.N. peacekeeping operations, the top 10 financial contributors, and other nations.

"People and communities under threat, with nowhere to go, need to know the U.N. will do anything within its scope to provide protection," Netherlands Foreign Minister Bert Koenders told the meeting.

Rwanda's U.N. Ambassador Eugene-Richard Gasana said the principles bring peacekeeping "into the 21st century."

"The reality is conflicts are escalating in numbers, and changing in nature at levels and speed that are unprecedented," he said. "We must meet these challenges head-on by adapting and modernizing our ways."

He said more than 6,000 Rwandan troops in U.N. peacekeeping missions are trained to follow the principles and "are prepared to use force when necessary" to protect civilians.

"What is most at stake is not our reputation or the legacy we intend to leave behind," Gasana said, "but rather the life of those civilians that have involuntarily been absorbed in conflicts and wars that have taken their loved ones, endangered their lives, stolen their livelihoods."