The United States government is getting involved in Apple's appeal of a ruling from the European Commission that could force the company to pay €13 billion in back taxes. Reuters says the government filed an application with the General Court of the European Union to intervene in the case.

It's unclear when the application was filed, so it could have been submitted during the Obama or Trump administrations.

The European Commission came to its significant ruling last year after a three-year investigation into Apple's tax deal with Ireland. Even though the country has a corporate tax rate of 12.5%, Apple paid an estimated rate of 0.005 to 1% from 2003 to 2014.

Apple filed an appeal in December and Ireland itself has challenged the ruling, arguing it never gave Apple a special deal.