DALLAS (AP) — American Airlines and United Airlines say they have asked the Trump administration not to put migrant children who have been separated from their parents on their flights.

The CEOs of both airlines said that the administration’s recent immigration policy of separating migrant families conflicts with their values.

We have no desire to be associated with separating families, or worse, to profit from it,” American Airlines CEO Doug Parker said in a statement.

United issued a statement in which CEO Oscar Munoz said the company’s purpose is to connect people. “This policy and its impact on thousands of children is in deep conflict with that mission and we want no part of it,” he said.

President Donald Trump told reporters he would sign an executive order Wednesday to end the practice of separating children from families after they are detained crossing the border illegally.

Since the White House announced a “zero-tolerance” policy toward undocumented migrants in early May, more than 2,300 children have been taken from their parents at the U.S.-Mexico border, leading to a spike in the number of young children under government care.

Both Parker and Munoz said they do not know whether any migrant children have been on their flights. In recent days several flight attendants have gone on social media to report seeing groups of children on their flights whom they believed to be children separated from their migrant families.

Many airlines have contracts to provide travel services to the U.S. government. Parker said, however, that the government doesn’t provide information about the passengers or their reason for travel.

Representatives of the Department of Homeland Security did not immediately respond to messages seeking comment.