The United States made a $500 million payment Tuesday to the U.N. Green Climate Fund, three days before handing over power to a new president who has called global warming a "hoax."
President Barack Obama made a $3 billion pledge to the fund in 2014. Tuesday's $500 million was the second payment in fulfilling that pledge.
"The GCF supports developing nations in their efforts ... to become more resilient to climate change, ... reducing the global and national security risks associated with inadequate adoption and preparedness for extreme weather events and other climate-related impacts," State Department spokes John Kirby said.
Kirby later told reporters there was no "nefarious desire" to provoke a reaction from the new administration by announcing the payment three days before Donald Trump takes over.
It is possible that the Trump administration could decide to withhold the rest of the U.S. pledge to the fund.
Trump has threatened to tear up the Paris climate change agreement.
But his nominee for secretary of state, Rex Tillerson, said at his confirmation hearing last week that it is important for the U.S. to have a "seat at the table" in tackling global warming.