Amazon says that it’s a company committed to fighting climate change, and recently it pledged to drastically reduce its carbon emissions over the next 20 years. But privately, the company has been punishing employees who speak out on the issue.

In recent months, Amazon management has threatened to fire at least two employees who criticized the company’s environmental policies in the press, as first reported by the Washington Post. The workers are leaders of an internal group of Amazon employees who helped organize participation in a historic global climate strike in September. Around the time of the walkout, the employees told the media that Amazon is contributing to climate change by supporting gas and oil company extraction with its cloud computing projects.

Now, some of the company’s employees say they see Amazon’s quiet reproach of these employees as an attempt to stifle workers’ feedback at a time when tech employees are more than ever before organizing and publicly holding their employers to ethical standards over issues like corporate carbon emissions, using technology for warfare, and sexual harassment in the workplace. (Google has similarly been accused of cracking down on growing dissent among its rank-and-file employees.)

While Amazon’s employee crackdown may be an attempt to contain controversy and tamp down on internal dissent, it may be having the opposite effect. According to several sources at the company, employees are continuing to organize and discuss Amazon’s climate policies on internal listservs, and many are publicly supporting the employees who have been reprimanded for speaking to the press.

“This is not the time to shoot the messengers,” Maren Costa, a principal user-experience designer at Amazon, said in a press statement released by members of the employee activism group Amazon Employees for Climate Justice (AECJ). Costa was one of three employees named in the Washington Post article who said they were warned for discussing Amazon in the media. “This is not the time to silence those who are speaking out,” Costa wrote.

In November, Costa told the Washington Post she was called into a meeting with Amazon HR, who told her she had violated a company policy that prohibits employees from speaking to the press without prior approval from the company. HR then sent a follow-up email, saying that a future violation could “result in formal corrective action, up to and including termination.” At least one other employee, Jamie Kowalski, told the Post he received a similar note. And a third employee organizer on climate change, Emily Cunningham, said she was warned in a meeting for her social media activity and for speaking to the press about Amazon.

A spokesperson for Amazon gave the following statement in response to accusations that the company was punishing activists for speaking out.

“This action was part of the normal business practice of alerting employees when they may have (knowingly or unknowingly) violated a policy. These conversations were about ensuring awareness and understanding of the policy.”

In September, a day after hundreds of Amazon employees announced their participation in a climate protest, the company announced internally that it had updated its company policy on external communications. Previously, employees had to receive approval via email from a senior vice president if they wanted to speak to the press. Since the change, employees now have to receive approval by making a request through a company intranet page, and the form now requires employees to give a business justification for their request. While Amazon says the policy makes it easier for employees to talk to the press, some employees say it’s being used to suppress public criticism of the company.

“After the Climate Pledge, I did not expect this policy to be used to silence the necessary discussion of Amazon’s contribution to climate change,” Weston Fribley, a software engineer at the company, told Recode. “Amazon’s policy lets the company unilaterally dictate who is allowed to have a voice in the conversation about climate change.”

In September, Amazon announced a major initiative to offset all of its carbon emissions by 2040 — notably, the change came just a day before 1,500 of its workers planned to walk out of its offices to support climate change. But many Amazon employees, organizing under the AECJ group, continue to push the company to go further. They want to see Amazon stop its work with oil and gas companies to develop software products that accelerate oil and gas extraction. They want it to make a commitment to end funding climate-denying politicians and organizations, and they are pushing for Amazon to reach its emission goal by 2030 — 10 years sooner than the company’s stated goal of 2040.

The revelation that the company has been punishing leaders agitating for these changes has so far revived discussion of these topics. Several employees publicly criticized Amazon’s actions to silence employees on climate change, stating messages of support in a press statement released by AECJ.

According to one employee who is involved with organizing efforts but who asked to remain anonymous, the company’s move to warn some of the most outspoken leaders “may quiet a few people down, but ultimately the folks that are most active are hard to intimidate. Most of us could be fired and not have it really hurt our lives. We could find a job somewhere else — and it would be really messy for Amazon.”

In addition, the employee told Recode that if the company continues to restrict employee organizing, it could offer fodder to the politicians and regulators who are growing increasingly critical of Big Tech’s power. Amazon is currently facing a high-profile antitrust investigation led by the Federal Trade Commission.

“The world is more and more leery of our impact and actively talking about breaking us up and regulating us more aggressively. Companies using their power to stifle employees burns our goodwill with the public,” the employee said.

Update 01/02/2020 5:14 PM ET: This article was updated with a statement from an Amazon spokesperson.