Senator Elizabeth Warren (D-MA) sent Apple CEO Tim Cook a letter asking for information regarding Cook and Apple’s conversations with President Donald Trump’s administration about tariffs and any special exemptions from the tariffs,

Senator Elizabeth Warren on Wednesday questioned Apple Inc. Chief Executive Officer Tim Cook on his discussions with the Trump administration ahead of the president’s retreat on tariffs covering crucial Apple products built in China.

Apple’s CEO Tim Cook spoke to Commerce Secretary Howard Lutnick last week about the potential impact of the tariffs on iPhone prices.