Power told reporters in her final news conference that "countries like Russia and China" would benefit from Washington's reduced standing at the UN.
Power told reporters in her final news conference that "countries like Russia and China" would benefit from Washington's reduced standing at the United Nations if funding were withdrawn.
"We lead the world in part by leading at the UN," said Power, who is stepping down next week after four years as President Barack Obama's ambassador to the United Nations.
"If we were to tie our hands behind our back or strip this organization of programming" to support peace mediation or humanitarian work, "this would be extremely detrimental to US interests", she said.
Power spoke after a bill was introduced in the US Senate that would slash all US funding to the United Nations until a Security Council resolution demanding an end to Israeli settlements is repealed.
"The United States needs the UN," Power said.
"The UN goes to places that the US will not go," she argued, pointing to peace missions in Africa.
The United States is by far the UN's biggest financial contributor, providing 22 percent of the its operating budget and funding 28 percent of peacekeeping missions which currently cost $8 billion annually.
Trump, who will be inaugurated next Friday, has dismissed the United Nations as "just a club for people to get together and have a good time."
After the council voted to demand an end to Israeli settlements in Palestinian territories, Trump warned "as to the UN, things will be different after Jan. 20th".