New York City Mayor Bill de Blasio said Monday that New Yorkers will be at risk of terror if Attorney General Jeff Sessions follows through on cutting federal law enforcement grants to sanctuary cities.

Sessions appeared at the White House to say that jurisdictions that ignore immigration detainers will lose Department of Justice grants, which total $4.1 billion for the upcoming fiscal year.

“President Trump’s latest threat changes nothing. We will remain a city welcoming of immigrants who have helped make our city the safest big city in the nation,” de Blasio said in response. “Any attempt to cut NYPD funding for the nation’s top terror target will be aggressively fought in court. We won’t back down from protecting New Yorkers from terror – or from an overzealous administration fixated on xenophobia and needless division.”

The attorney general, on the other hand, argued that sanctuary cities make America more dangerous. “Countless Americans would be alive today if these policies of sanctuary cities were ended,” Sessions said.

He pointed to a recent report from the Department of Homeland Security which highlighted over 200 cases of local law enforcement agencies refusing to turn serious criminals over to federal immigration officers.