Why is PRESIDENT DONALD TRUMP sending ICE into SANCTUARY CITIES?

Why is PRESIDENT DONALD TRUMP sending ICE into SANCTUARY CITIES? This is not ROCKET SCIENCE, PRESIDENT DONALD TRUMP is sending ICE into SANCTUARY CITIES because that were they are at? https://www.ktvu.com/news/sanctuary-cities-brace-more-ice-raids-after-trumps-latest-threat NATIONAL ASOCIATION FOR THE ADVANCEMENT OF WHITE PEOPLE