Embattled Attorney General Jeff Sessions announced on Tuesday that cities that prevent Immigration and Customs Enforcement agents from entering prisons and jails will be subject to losing large amounts of federal funds.

The funds at risk are those known as Edward Bryne Memorial Justice Assistance Grants or JAG grants.

"So-called ‘sanctuary' policies make all of us less safe because they intentionally undermine our laws and protect illegal aliens who have committed crimes," Sessions said in a statement.

"This is what the American people should be able to expect from their cities and states, and these long overdue requirements will help us take down MS-13 and other violent transnational gangs, and make our country safer," he added.

Cities must meet three requirements to be eligible for the JAG grants, according to a Justice Department official:

Prove compliance with a federal statute showing they do not block law enforcement officers from sharing immigration status information with ICE Allow Department of Homeland Security officers — i.e. ICE agents — into any detention center Give DHS/ICE a 48-hour notice before releasing anyone for whom ICE requested a detainer

The new limits on JAG grants do not begin until fiscal 2017, the Justice Department said.

The change makes good on repeated promises from both Sessions and President Trump to crack down on so-called sanctuary cities.

But it also comes at a time when tensions between the Justice Department in the White House are at an all-time high.

Trump has come out against Sessions — who he has called "beleaguered" — multiple times in interviews, news conferences and on Twitter. The president has not said yet if he will fire Sessions, but has said he is "disappointed" in Sessions's decision to recuse himself from the Justice Department's investigation into Russian meddling in the 2016 presidential election.

Sessions has made no indication he will resign, and Tuesday's move shows he is still prepared to carry out policy promises made by Trump during his presidential campaign.

Sessions has come out against so-called sanctuary cities before in numerous speeches as part of his tough immigration rhetoric.