British Prime Minister Theresa May threatened Wednesday to hold back 30 percent of her country's UN contributions unless the world body undertakes drastic reform.
"If this system that we have created is found to no longer be capable of meeting the challenges of our time, then there will be a crisis of faith in multilateralism and global cooperation that will damage the interests of all our peoples," May said before the General Assembly in New York.
The UK is the second largest UN funder, and May said the withheld funds will be dispersed "only to those parts of the UN that achieve sufficient results".
"Despite our best efforts, we are not succeeding. We must do more," she said, urging reform.
May spoke highly of the UN-centric international system, calling it "the amplifying force that allows countries to cooperate and live up to these standards in words, spirit and deed".
But in pointing out its shortcomings, May made veiled mention to Russia when she called out one Security Council member who she said has used its veto power as many times in the past five years as during the second half of the Cold War.
"In so doing, they have prevented action against a despicable regime that has murdered its people with chemical weapons," she said. "As a result, in Syria, the United Nations has been blocked."
She took a further swipe at U.S. President Donald Trump, criticizing him for moving to pull the U.S. out of the historic Paris climate accord, which she said is an example of how nations can join together to pursue "fairness, justice and human rights".
"It is this rules-based system which we have developed — including the institutions, the international frameworks of free and fair trade; agreements such as the Paris climate accord; and laws and conventions like the Non-Proliferation Treaty — which enables the global cooperation through which we can protect those values,” she said.