In her first interview since resigning in May, former U.S. ambassador to Mexico, Roberta Jacobson, gives a blistering critique of the Trump administration's "zero-tolerance" immigration agenda. Jacobson tells NPR's Lulu Garcia-Navarro enforcement actions that result in children being separated from their parents, as well as a recent decision to narrow the definition of what qualifies someone for asylum, are "draconian" and "un-American."

She says Trump's immigration policies are among the "many reasons" she chose to resign after serving for less than two years as America's top diplomat to Mexico.

"It is very difficult to see how these policies either help the United States or the countries from which the migrants are coming," Jacobson says.

"Unless the administration can address the reasons why migrants from Mexico and Central America are coming to the U.S., she says, "no amount of draconian and frankly, un-American policies, as I believe these are, is really going to make a permanent difference, but it may affect our own standing in the world and certainly in the region."

Jacobson's comments add to a chorus of criticism that has faced the administration since April when Attorney General Jeff Sessions outlined "a zero-tolerance policy" in which anyone caught crossing the U.S.-Mexico border illegally would face prosecution. The approach has come under fire as a growing number of children has been separated from their parents as a result of the policy. Between April 19 and the end of May, a total of 1,995 minors were separated from their "alleged adult guardians," according to the Department of Homeland Security.

Trump has blamed Democrats for "forcing the breakup of families," yet no law requires children to be taken from their parents if they cross the border illegally. The president has called the separations "cruel," but when asked about the policy this week, White House spokeswoman Sarah Sanders said "it is very biblical to enforce the law." Sessions has also cited the Bible in defending the policy.

The administration came under additional criticism this past Monday following a decision by Sessions to impose new limits on who can gain asylum in the U.S., ruling that most migrants fleeing domestic abuse or gang violence will not qualify.

Jacobson says, however, that her decision to resign was about more than just immigration alone. She said she encountered "increasing difficulty" in defending the administration's policies toward Mexico, "and in trying to work in what one might call sort of regular order with the Mexican government, that was quite keen to work with us and quite willing to have a deeper and more productive relationship ... only to see that sort of blown up periodically by tweets or rallies about the wall or about characterizing Mexicans."

Jacobson, who spent more than three decades at the State Department, says she "tried mightily to influence decisions" and establish a more cooperative relationship between the Trump administration and the Mexican government, but said she struggled to do so under former Secretary of State Rex Tillerson, who she called "difficult to reach."

Jacobson calls Tillerson's successor, Mike Pompeo, "more accessible in general," but conceded that she was unfamiliar with his views on Mexico.

The former ambassador says she was also stymied by the White House's decision to channel recent talks with the Mexican government through Trump's son-in-law, Jared Kushner. In March, Kushner traveled to Mexico to meet with President Enrique Peña Nieto and Foreign Secretary Luis Videgaray, but according to media reports, Jacobson was not invited to join those conversations.

"It's always problematic for an ambassador to be left out of meetings like that. It gives me no great joy to admit that," Jacobson says. "When someone who is clearly the lead on the policy issue on Mexico comes to the capital and you're not in the meeting with the foreign secretary or the president, it's a signal to a foreign government that you are not as important, that you can be ignored."

Jacobson's comments come as the traditionally close relationship between the U.S. and Mexico has grown increasingly strained. Late last month, the Trump administration said it would impose tariffs of 25 percent on steel from Mexico, and tariffs of 10 percent on aluminum. Mexico hit back days later with tariffs on about $3 billion worth of American pork, steel, cheese and other goods.

Meanwhile, the two countries appear locked in a stalemate over the future of the North American Free Trade Agreement, which Trump is seeking to renegotiate, arguing that it disadvantages American workers.

On the issue of NAFTA, Jacobson says the negotiations are "one of the most difficult uncertainties" facing businesses in Mexico, the U.S. and Canada.

"I'm talking not just about Fortune 500 companies, but the small and medium sized enterprises, the mom and pop stores that export and are part of integrated supply chains," Jacobson says. "We know a lot about how the auto industry is integrated in North America, but there are dozens of other industries that are very integrated, and if NAFTA were to go away, they'd be adversely affected."

Jacobson says the U.S. is "testing the limits of our cooperation" with Mexico, and warned that given the perception in Mexico that the government of Peña Nieto has not adequately stood up to Trump, the next administration could be much less accommodating.

"I don't think there's any doubt that any president who's elected in Mexico this July will have to push back harder than the current administration did."

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