Google fired 28 employees in connection with sit-in protests at two of its offices this week, according to an internal memo obtained by The Verge. The firings come after 9 employees were suspended and then arrested in New York and California on Tuesday.

The fired employees were involved in protesting Google’s involvement in Project Nimbus, a $1.2 billion Israeli government cloud contract that also includes Amazon. Some of them occupied the office of Google Cloud CEO Thomas Kurian until they were forcibly removed by law enforcement. Last month, Google fired another employee for protesting the contract during a company presentation in Israel.

In a memo sent to all employees on Wednesday, Chris Rackow, Google’s head of global security, said that “behavior like this has no place in our workplace and we will not tolerate it.” You can read the full memo at the bottom of this story.

He also warned that the company would take more action if needed: “The overwhelming majority of our employees do the right thing. If you’re one of the few who are tempted to think we’re going to overlook conduct that violates our policies, think again. The company takes this extremely seriously, and we will continue to apply our longstanding policies to take action against disruptive behavior — up to and including termination.”

In a response statement, the “No Tech for Apartheid” group behind the protests called Google’s firings a “flagrant act of retaliation.”

“In the three years that we have been organizing against Project Nimbus, we have yet to hear from a single executive about our concerns,” the group wrote in a post on Medium. “Google workers have the right to peacefully protest about terms and conditions of our labor. These firings were clearly retaliatory.”

You can read Rackow’s full memo below:

Serious consequences for disruptive behavior

Googlers,

You may have seen reports of protests at some of our offices yesterday. Unfortunately, a number of employees brought the event into our buildings in New York and Sunnyvale. They took over office spaces, defaced our property, and physically impeded the work of other Googlers. Their behavior was unacceptable, extremely disruptive, and made coworkers feel threatened. We placed employees involved under investigation and cut their access to our systems. Those who refused to leave were arrested by law enforcement and removed from our offices.

Following investigation, today we terminated the employment of twenty-eight employees found to be involved. We will continue to investigate and take action as needed.

Behavior like this has no place in our workplace and we will not tolerate it. It clearly violates multiple policies that all employees must adhere to — including our Code of Conduct and Policy on Harassment, Discrimination, Retaliation, Standards of Conduct, and Workplace Concerns.

We are a place of business and every Googler is expected to read our policies and apply them to how they conduct themselves and communicate in our workplace. The overwhelming majority of our employees do the right thing. If you’re one of the few who are tempted to think we’re going to overlook conduct that violates our policies, think again. The company takes this extremely seriously, and we will continue to apply our longstanding policies to take action against disruptive behavior — up to and including termination.

You should expect to hear more from leaders about standards of behavior and discourse in the workplace.