President Donald Trump renewed his complaints about homelessness Tuesday during a swing through California, talking about the harm it does to taxpayers seeking prestigious real estate and warning that cities will "destroy themselves" if his administration doesn’t intervene.

The homeless are living in "our best highways, our best streets, our best entrances to building," Trump told reporters traveling aboard Air Force One with him to a string of fundraisers in California. "People in those buildings pay tremendous taxes where they went to those locations because of the prestige.”

Trump went on to say he has been talking to "foreign people, foreign tenants" in California who want to leave the country because of the homeless problem. Trump has been increasingly raising concern about homelessness, and said the White House would be taking some sort of action soon.

"In many cases they came from other countries and they moved to Los Angeles or they moved to San Francisco because of the prestige of the city, and all of a sudden they have tents," Trump said. "Hundreds and hundreds of tents and people living at the entrance to their office building. And they want to leave. And the people of San Francisco are fed up, and the people of Los Angeles are fed up. And we’re looking at it, and we’ll be doing something about it."

Trump’s administration sent officials earlier this month to California to look into the problem there, but it is unclear how much the federal government can do on an issue that is mostly the responsibility of state and local governments and law enforcement. Trump said he has been taking to Ben Carson, the secretary of Housing and Urban Development, about potential solutions.

California Gov. Gavin Newsom, a Democrat, asked Trump on Monday to approve more housing vouchers through two existing programs and to increase the value of the vouchers to help people cope with rising rents.

Trump is attending fundraisers in California Tuesday in Beverly Hills and Palo Alto and Wednesday will meet with donors at events in Los Angeles, and San Diego.