Donald Trump will not deploy federal agents to San Francisco, the U.S. president and the California city’s mayor said in separate social media posts on Thursday, a surprising stand-down as Trump pressures Democratic-led cities around the country to step up enforcement against crime and illegal immigration.

Air traffic control staffing issues are delaying travel at airports in New York, Washington, Newark and Houston, the U.S. Federal Aviation Administration (FAA) said late on Thursday, as a U.S. government shutdown hit its 23rd day.