LONDON, UK: The United States has pulled out of international talks in London about reducing pollution from ships. These talks are part of a global effort to make the shipping industry carbon neutral by around 2050.

A U.S. government message seen by Reuters said Washington may take "reciprocal measures" if American ships are charged fees related to their fuel or emissions. The message also said the U.S. will not join negotiations at the U.N.'s International Maritime Organization (IMO) this week.

A U.S. State Department spokesperson confirmed that the U.S. won't take part in the talks and said the government wants to protect American interests in any global agreement.

Some countries, including those in the European Union, want to create the world's first carbon tax for shipping. But the U.S. said it strongly disagrees with any plan that would put extra costs on U.S. ships based on emissions or fuel use.

The U.S. note asked other countries to reconsider supporting these proposals and said that if such "unfair" fees are approved, the U.S. may take steps to make up for the cost and protect Americans.

The U.S. also opposes using money raised from shipping fees to pay for unrelated environmental projects.

Shipping moves about 90 percent of global trade and creates nearly 3% of the world's carbon emissions. Environmental groups and investors have pushed for stronger action, including a carbon fee.

Even with the U.S. stepping back, talks at the IMO are continuing. One delegate from the Marshall Islands said that while the U.S. is important, one country shouldn't stop progress for everyone else.

Other countries like China and Brazil also oppose a fixed carbon fee, saying it would hurt developing economies that rely on trade.

In January, President Donald Trump withdrew the U.S. from the Paris climate agreement again, taking the U.S. out of the main international effort to fight climate change.