After meeting with Central American officials in Guatemala City last week, Vice President Joe Biden had a message for anyone considering crossing the border illegally into the United States: Don't do it.

"It will not be open arms," Biden said. "We're going to hold hearings with our judges, consistent with international law and American law, and we're going to send the vast majority of you back."

That is the new, official, get-tough message of the Obama administration in response to the growing crisis of tens of thousands of young people entering the country illegally. But despite talk of a so-called "surge" in border enforcement, the administration's record is probably a good predictor of what is to come. And the fact is, the U.S. is sending very, very few young illegal border-crossers home.

In a White House-arranged conference call last Friday, Homeland Security officials announced that from last October to this month, 52,000 unaccompanied children have been caught crossing the U.S.- Mexico border. Experts expect that number to grow to 90,000 by later this year -- and that does not include the children coming in with a parent or family member. Almost all are coming from Guatemala, Honduras or El Salvador.

One key question in the current debate is, how many have been sent back? Homeland Security won't say. But we have some clues.

A leaked May 30 internal memo written by a top Border Patrol official, Deputy Chief Ronald Vitello, said, "Currently only three percent of apprehensions from countries other than Mexico are being repatriated to their countries of citizenship, which are predominantly located in Central America." That three percent is nowhere near the "vast majority" Biden promised.

In his brief statement, the vice president (unintentionally) put his finger on the problem. "We're going to hold hearings," he said, "with our judges, consistent with international law and American law." That hearing process now stretches for years, ensuring that a young illegal immigrant will not have to leave the U.S. anytime soon, if at all.

"It's taking a year or more in some places for these people to come up on a hearing," says Gary Mead, a former head of Enforcement and Removal Operations for Immigration and Customs Enforcement. "And many times, they don't have an attorney, or they've lost an attorney, and they get an extension, and maybe it's two years before they have a hearing. And in the interim period, they enroll in school, or they get a job, or they are reunited with family members, and then they are no longer an enforcement priority."

Even if, after two or three years, a hearing judge finally orders removal, many illegal immigrants just ignore the order. No one makes them leave.

The number of minors — the ones now flooding the border — removed in this way is tiny, measured in the hundreds for Guatemala, Honduras and El Salvador combined. According to Jessica Vaughan, director of policy studies at the Center for Immigration Studies, the United States deported a total of 802 minors to those three countries in 2011; 677 in 2012; and 496 in 2013. Even if, with the administration's new enforcement "surge," that number were to soar to, say, 1,200, it would be nothing compared to the number of young people coming in.

"If you're getting 90,000 a year, or 50,000 a year, or even 25,000 a year, and you only remove 1,200, you're not eliminating the backlog," Mead notes dryly.

So the slow-moving American system, combined with President Obama's well-publicized desire to stop deportations of people who come to the United States illegally at a young age, basically makes it impossible for Joe Biden's pledge — "We're going to send the vast majority of you back" — to be true.

Just as they have for years, potential illegal immigrants will get the message that the new U.S. enforcement campaign isn't serious. And that will likely make the problem worse.

In the internal Border Patrol memo, Vitiello stressed that the only way to stop the flow is to show potential illegal immigrants — or, in the cases of the youngest, the family members who send them — that there will be real consequences for their actions. "If the U.S. government fails to deliver adequate consequences to deter aliens from attempting to illegally enter the U.S.," Vitiello wrote, "the result will be an even greater increase in the rate of recidivism and first-time illicit entries."

No matter what Joe Biden says.