The agreement is currently under negotiation and would be a “free trade” type of agreement between the United States and eight other Pacific countries aimed at cutting costs by measures such as making other countries’ regulatory systems more similar to that of the United States to help U.S. industry, according to the U.S. trade representative’s website.

In the letter, the Alliance for American Manufacturing and nine other groups said that currency manipulation used as a way to gain an unfair competitive advantage is one of the most “trade-distorting” practices, and that competitive devaluation of currency can impede open trade.   

Deliberately weakening a currency, like the Chinese did in 2010 with the yuan, allows a country to export its products at a much lower price, therefore undercutting the sales of competitors in other countries, according to CNN.

“Creating a level playing field for U.S business to access markets abroad will be fundamental to achieving America’s goal of doubling exports by 2014,” the groups said in the letter. “Addressing currency manipulation in future U.S. free trade agreements will go a long way to supporting this objective.”