As President Donald Trump pressures Mexico to address the flow of migrants and drugs heading north into the United States, the Supreme Court is set to hear arguments Tuesday in a major appeal about one thing that’s crossing the border toward Mexico: guns.

The dispute focuses on whether Mexico can hold U.S. manufacturers liable for gun violence and comes amid rising tensions between the countries.

The US Supreme Court will hear arguments in Mexicos lawsuit against American gun manufacturers today. Mexico alleges that US gun makers knowingly facilitate arms trafficking across the borders, leading to violence in the country.