Standing in the Rose Garden on Thursday at the White House, President Donald Trump outlined his reasons for withdrawing the United States from the 2015 Paris Agreement on climate change.
More than 190 countries have committed to the deal that aims to reduce global greenhouse gas emissions.
Mr Trump noted the potentially "tens of billions of dollars" that the US was required to spend on the Green Climate Fund - set up to raise money from the wealthiest nations to be spent on environmental projects in developing countries. Established in 2011, 43 countries have now pledged to the fund, raising $10bn (£7.8bn) to date. Mr Trump complained that other countries had not paid and that the agreement was against America's interests.
The US has spent more than any other country. However, there is no obligation for countries to pay into the fund, as it is voluntary.
What is the Green Climate Fund for?
So far, money from the fund has gone on projects across the world including water conservation in Morocco and helping farmers tackle extreme weather in Sri Lanka.
As Mr Trump noted, the United States has pledged $3bn (£2.3bn) and actually spent $1bn (£776m) so far.
President Obama submitted the second half of that amount only three days before Mr Trump's inauguration. It came from the State Department's Economic Support Fund (ESF), which finances a range of development, security, counter-terrorism and humanitarian projects to advance political and strategic interests in countries such as Iraq, South Sudan, Colombia and Afghanistan.
Mr Trump said funding was "raided out of America's budget for the war against terrorism". Although money from the ESF could be used in counter-terrorism, it is not the main source of funding for America's war against terrorism - that is the defence budget.
As Mr Trump noted in his speech, one goal of the Paris Agreement was to raise $100bn (£77.7bn) a year by 2020 to support climate action in developing countries, first discussed as a target in 2010. The money would be used to help poorer countries invest in green energy and renewable technology.
The Green Climate Fund is one mechanism set up to raise money to reach that annual target.
Which countries have pledged the most?
US - $3bn (£2.3bn)
Japan - $1.5bn (£1.2bn)
UK - $1.2bn (£931m)
France - $1bn (£776m)
Germany - $1bn (£776m)
Source: Green Climate Fund
The UK has paid about £400m into the fund so far, and Japan nearly half of its pledged amount. However, this does not necessarily paint the same picture if you take the population size of the countries into account. According to the Green Climate Fund's tracker, the US pledge amounts to just over $9 (£7) a person. Sweden's pledge represents almost $60 (£47) per person, the highest out of any country. The UK has proposed almost £15 a person. India and China have not put forward any cash into the Green Climate Fund.
China has made available significant funds for a different fund to help developing countries combat climate change.