More than 100 employees of technology companies including Alphabet‘s Google, Twitter, and Salesforce.com pledged on Tuesday to not help U.S. President-elect Donald Trump’s administration build a data registry to track people based on their religion or assist in mass deportations.
Drawing comparisons to the Holocaust and the internment of Japanese Americans during World War II, the employees signed an open letter at neveragain.tech rebuking ideas floated by Trump during the campaign trail. The protest comes a day before several technology company executives are due to meet with the real-estate developer in New York City.
“We are choosing to stand in solidarity with Muslim Americans, immigrants, and all people whose lives and livelihoods are threatened by the incoming administration’s proposed data collection policies,” reads the letter, signed by a mix of engineers, designers and business executives.
It continues: “We refuse to build a database of people based on their Constitutionally-protected religious beliefs. We refuse to facilitate mass deportations of people the government believes to be undesirable.”
The letter vows to not participate in creating databases of identifying information for the U.S. government on the basis of race, religion, or national origin, to minimize the collection or retention of data that could facilitate such targeting and to oppose any misuse of data at their respective organizations considered illegal or unethical.
Get Data Sheet, Fortune’s technology newsletter.
Trump clashed with Silicon Valley on several issues during the campaign, including immigration, government surveillance, and encryption, and his victory last month alarmed many companies who feared he might follow through on his pledges.
Those concerns have not been assuaged in recent weeks, as Trump has said he intends to nominate individuals to senior posts in his administration who favor expanding surveillance programs.
Read more: Carly Fiorina Abandons Her Defense of Women For Possible Trump Cabinet Post
Alphabet (GOOGL) Chief Executive Officer Larry Page, Apple (AAPL) CEO Tim Cook, Facebook (FB) Chief Operating Officer Sheryl Sandberg and Amazon.com (AMZN) CEO Jeff Bezos and Oracle (ORCL) CEO Safra Catz are among those expected to attend the summit with Trump’s transition team, according to two technology industry sources.
The Trump transition team did not respond to a request for comment regarding the open letter.