The Washington Post is reporting that Amazon has warned at least two employees for speaking out against its climate policies.

In September, Amazon CEO Jeff Bezos (who owns the Washington Post) announced The Climate Pledge, the company’s commitment to meet the Paris Agreement 10 years early. In spite of that, some employees have been critical of the company’s climate efforts, two of whom were quoted in a previous Washington Post article.

Evidently, Amazon did not take kindly to two of its employees criticizing the company.

According to the Washington Post, “a lawyer in the e-commerce giant’s employee-relations group sent a letter to two workers quoted in an October Washington Post report, accusing them of violating the company’s external communications policy. An email sent to Maren Costa, a principal user-experience designer at the company, and reviewed by The Post warned that future infractions could ‘result in formal corrective action, up to and including termination of your employment with Amazon.’”

The company defended its external communication policy as “similar to other large companies,” according to a spokeswoman. In spite of that, Costa vowed to continue speaking up and fighting the company’s censorship.

This is just the latest in what has been termed “employee activism,” where employees hold the companies they work for responsible for their actions. With this trend on the rise, companies have had to be far more careful to take their employees’ values into consideration when making decisions.

“No company today is completely immune to these types of risks, so the issue is how to minimise their potential and recover quickly if damaging events occur,” Leslie Gaines-Ross, Chief Reputation Strategist at PR firm Weber Shandwick, told CEO Magazine.

Amazon may find itself in a sticky situation if it fails to deliver on its Climate Pledge, or engages in other things that undermine it.