Some 130 lawmakers sent President Obama a letter on Monday expressing their opposition to a pending arms trade treaty if it impinges on gun rights and U.S. sovereignty in any way.

The United Nations this week begins a month-long process of crafting a long-delayed treaty to create international standards for importing and exporting conventional weapons. Proponents say the treaty would bring much of the rest of the world in line with U.S. standards without affecting domestic sales, but gun enthusiasts are worried.

“The UN’s actions to date indicate that the ATT [United Nations Arms Trade Treaty] is likely to pose significant threats to our national security, foreign policy, and economic interests as well as our constitutional rights,” reads the letter, which was spearheaded by Rep. Mike Kelly (R-Pa.). “The U.S. must establish firm red lines for the ATT and state unequivocally that it will oppose the ATT if it infringes on our rights or threatens our ability to defend our interests.”