The United States is announcing its support for 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 told a high-level U.N. meeting Wednesday focusing on the responsibility to protect civilians that the United States was "proud" and "humbled" to join 28 other countries that have pledged to abide by the 18 pledges.

U.N. peacekeepers from these 29 countries are now required to act in cases where civilians are in danger.

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