Jeff Sessions, U.S. attorney general, left, speaks as Tom Homan, deputy director of U.S. Immigration & Customs Enforcement (ICE), listens during a press conference regarding immigration policy in San Diego, California, U.S., on Monday, May 7, 2018.

A strict new enforcement plan by the Trump administration will mean more parents caught illegally crossing the U.S. border will get prosecuted and separated from any children accompanying them.

"I have put into place a zero tolerance for illegal entry on our southwest border," said Attorney General Jeff Sessions in remarks Monday at the San Diego border. "If you cross the border unlawfully, then we will prosecute you. It's that simple."

Added Sessions, "If you smuggle illegal aliens across our border, then we will prosecute you. If you are smuggling a child, then we will prosecute you. And that child maybe separated from you as required by law."

Sessions said the U.S. Department of Homeland Security would now be "referring 100 percent of illegal southwest border crossings to the Department of Justice for prosecution. We need legality and integrity in our immigration system."

Hecklers could be heard drowning out some of Sessions comments during his remarks at Monday's news conference.

"This is not about family separation," said a DHS official, who didn't wish to be named. "This is all about referring people for prosecution who break our nation's immigration laws."

But the DHS official conceded one effect of the tougher new policy is it will result in separation of families who illegally cross the southwest border.

The Wall Street Journal reported Monday that the strict new policy has been under discussion for months, but added that the administration postponed announcing it "because of the sensitivities of removing children from their parents."

"This department, under President Trump's leadership, is enforcing the law without exception," said Sessions. "We will finally secure this border so that we can get the American people the safety and peace of mind that they deserve."

Sessions was accompanied at Monday's press conference at the border by Thomas Homan, the deputy director and acting head of the U.S. Immigration and Customs Enforcement. Homan is retiring this summer and took issue with reports the administration had changed any policies regarding separating families.

Said Homan, "I want to be clear, DHS does not have a blanket policy on separating families as a deterrent."

According to Homan, DHS has "always separated families" under two specific situations: first, when the government can't establish the adult is the parent or when a child is being trafficked; and second, when a parent is prosecuted the child in separated.

"This has always been the policy," Homan said. "Now you will see more prosecutions because the attorney general's commitment to 'zero tolerance.'"

Homan, surrounded by immigration and enforcement agents, also addressed protesters making noise at the press conference.

"I usually don't address hecklers but i want to address this one," said Homan. "The only shame in this media event is people that want to call out American patriots — men who stand around me in all these uniforms that strap a gun to their hip every day."

Homan said the federal immigration agents "leave the safety and security of their homes every day to defend this nation and to defend the community. They're doing their sworn oath. That is our job. If people like to heckle or don't like what we do, then talk to your congressman and change the law."

Officials said the U.S. Customs and Border Protection (CPB) agency has seen sharp increase in the number of families and so-called unaccompanied alien children crossing the border illegally over the past 12 months. The official said the adult parents making illegal crossings with minors are "risking the lives of their children."

The attorney general said the actions announced Monday "are necessary and made even more necessary by the massive increases in illegal crossings in recent months."

This past month, the CBP said it has had contact with more than 50,000 immigrants seeking to illegally enter the United States.

Under the Department of Justice's "zero-tolerance policy," those persons apprehended for illegally crossing will get sent immediately to federal court under the custody of the U.S. Marshals Service. However, any children found illegally crossing with adults will get transferred to the custody of a refugee resettlement agency of the Department of Health and Human Services.

In March, the American Civil Liberties Union sued to the Trump administration in a class-action complaint that alleges the government is "forcibly separating asylum-seeking parents and young children." The ACLU argued the family separation case this past Friday in San Diego. No date for a decision has been announced.

Undocumented families seeking amnesty and allowed into the U.S. at a port of entry are usually allowed to stay together but go to detention facilities. There have recently been members of a caravan of migrants from Central America at the U.S.-Mexico border who have sought asylum, including children.

"Today, we're here to send a message to the world that we're not going to let the country be overwhelmed," Sessions said at the news conference. "People are not going to caravan or otherwise stampede our border. We need legality and integrity in our immigration system."

Sessions also warned that undocumented persons who cross the border and make false statements to a federal immigration officer or file a fraudulent asylum claim with the U.S. government face felony charges.

"So if you're going to come to this country, come here legally — don't come here illegally," the attorney general said.

As part of implementing the new policy, the DOJ is beefing up the number of prosecutors and judges to handle immigration cases in the southwest border region. A total of 35 prosecutors will be sent to the region and 18 immigration judges relocated to take on the new workload.

Sessions said there will be a roughly 50 percent increase in the number of judges that will also be handling asylum claims.

"I have no doubt that many of those crossing our border illegally are leaving behind difficult situations," said Sessions. But he added, "We cannot take everyone who wants to come here without also impacting the citizens and interests of the American people that we're sworn to protect."

Meantime, the DHS official said that when the U.S. government is "dealing with families that cross the border, our primary responsibility is to ensure the welfare of the children. Unfortunately, we continue to see too many cases of children being used by smugglers, traffickers and [transnational criminal organizations] in an attempt to circumvent our laws and gain entry."

The DHS official said that separation of families also "may occur when we are unable to determine the custodial relationship, when we determine that a child may be at risk with the custodian, or when the custodian is transferred to a criminal detention setting due to criminal charges. That is long-standing policy."