"Unfortunately some states and cities have adopted policies designed to frustrate the enforcement of immigration laws," including refusing to detain nonfelons on federal detainer requests, Sessions said.
Sessions noted a Department of Homeland Security report out last week showing more than 200 criminal suspects released in one week despite Immigration and Customs Enforcement detainers.
"Such policies cannot continue. They make our nation less safe by putting dangerous criminals back on the streets," he added.
"We intend to use all the lawful authorities we have to make sure our state and local officials … are in sync with the federal government," Sessions said.
"Moreover, the Department of Justice will require that jurisdictions seeking or applying for Department of Justice grants to certify compliance with [relevant laws] as a condition of receiving those awards," he added.
In the current fiscal year, Department of Justice's Office of Justice Programs is slated to award $4.1 billion in grants.
"I strongly urge our nation's states and cities and counties to consider carefully the harm they are doing to their citizens by refusing to enforce our immigration laws and to rethink these policies. Such policies make their cities and states less safe — public safety as well as national security are at stake — and put them at risk of losing federal dollars," he said.
He brought up the death of Kate Steinle, a woman who was allegedly shot and killed by an unauthorized immigrant on a San Francisco pier last summer. Donald Trump repeatedly cited her death during the presidential campaign when he called for an end to sanctuary cities.
"We have simply got to end this policy," Sessions said.
The Obama administration said that cities that don't honor the detainer laws put forth by ICE could lose federal funds, so Sessions is not the first to make this threat.