Earlier this week, AWS vice president Tim Bray quit over what he sees is an attempt to punish whistleblowers who express concerns about lacking COVID-19 protections. Meanwhile, the National Labor Relations Board is looking into claims of retaliation against employees who organize or participate in protests.

In a statement provided to Engadget, an Amazon spokesperson said:

“These individuals were not terminated for talking publicly about working conditions or safety, but rather, for violating—often repeatedly—policies, such as intimidation, physical distancing and more. We support every employees’ right to criticize or protest their employer’s working conditions, but that does not come with blanket immunity against any and all internal policies. We look forward to explaining in more detail in our response to the Senators’ letter.”

Amazon has responded to criticism around its coronavirus response with a pledge to provide masks and conduct temperature scans, and CEO Jeff Bezos said the company will spend $4 billion on COVID-19 related expenses, including “keeping employees safe.” But Amazon is facing pressure abroad too, and it is being questioned regarding alleged data abuse.

As The Verge notes, in the past, Amazon has justified firing outspoken employees with vague claims that they violated internal policies. But with increased pressure on several fronts and big names like Sanders and Warren behind this letter, Amazon may have to offer a more in depth explanation.

Update 5/7/2020 3:05PM ET: This story was updated to include a statement from Amazon.