Laura Bush is breaking her three-year silence on Donald Trump to call for a "kinder, more compassionate and more moral answer" to the current immigration policy that is tearing families apart at the border

In the three years since Donald Trump launched his presidential campaign with so much controversial bombast in 2015, Laura Bush has steadfastly kept her counsel about the polarizing first Republican in the White House since her own husband George W. Bush served two terms.

Trump’s treatment of migrant children is what broke the former First Lady’s resolve.

As images flooded social media this weekend to show how the Trump administration’s migration policy was tearing families apart at the border, Mrs. Bush took the unusual step of writing an opinion piece for the Washington Post that was published on Father’s Day. In it, she spoke out about the nearly 2,000 children who were separated from their families during a six-week period in April and May as the Trump administration adopted a “zero-tolerance” policy for illegal entry into the United States, TIME reported on Saturday.

“I live in a border state. I appreciate the need to enforce and protect our international boundaries, but this zero-tolerance policy is cruel. It is immoral. And it breaks my heart,” Bush wrote.

Her fellow former first lady, Michelle Obama, gave Mrs. Bush’s words a simple but ringing endorsement: “Sometimes truth transcends party,” Obama, a Democrat tweeted later on Monday. And by Monday evening, all four of the nation’s former first ladies had spoken out.

“The practice and policy today of removing children from their parents’ care at our border with Mexico is disgraceful and a shame to our country,” Rosalynn Carter said in a statement from Georgia. And Hillary Clinton, at a women’s forum in New York, called what’s happening a “moral crisis.”

Bush, in her op-ed saw similarities with the period of Japanese internment during World War II, which she said is “now considered to have been one of the most shameful episodes in U.S. history.”

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Laura Bush
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She also recalled when former First Lady Barbara Bush, her late mother-in-law, cuddled a dying baby while visiting a home for children with HIV/AIDS. “She, who after the death of her 3-year-old daughter knew what it was to lose a child, believed that every child is deserving of human kindness, compassion and love,” Bush wrote.

“Americans pride ourselves on being a moral nation, on being the nation that sends humanitarian relief to places devastated by natural disasters or famine or war,” said the former first lady. “We pride ourselves on believing that people should be seen for the content of their character, not the color of their skin. We pride ourselves on acceptance. If we are truly that country, then it is our obligation to reunite these detained children with their parents — and to stop separating parents and children in the first place.”

She continued, “People on all sides agree that our immigration system isn’t working, but the injustice of zero tolerance is not the answer. I moved away from Washington almost a decade ago, but I know there are good people at all levels of government who can do better to fix this.”

Bush’s brother-in-law, Jeb Bush, the former governor of Florida, joined her protest on Monday, tweeting that children were being “used as a negotiating tool” and Trump should end his “heartless” policy.

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Melania Trump
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In another surprising move from the first-lady realm, current First Lady Melania Trump, on Sunday released a statement about her husband’s controversial immigration policy.

“Mrs. Trump hates to see children separated from their families,” her communications director, Stephanie Grisham, told PEOPLE.

Grisham added that her boss calls on Democrats and Republicans to fix the nation’s immigration crisis.

“[She] hopes both sides of the aisle can finally come together to achieve successful immigration reform,” Grisham said, adding that Mrs. Trump “believes we need to be a country that follows all laws, but also a country that governs with heart.”

The spokeswoman did not immediately respond to follow-up questions from PEOPLE on Monday about what Mrs. Trump is doing to help change her husband’s policy.

Clinton, speaking at a luncheon of The Women’s Forum of New York, said: “I warned about this during the debates and on the campaign trail, that Trump’s immigration policies would result in families being separated, parents being sent away from their children, people being rounded up into trains and buses. And now, as we watch with broken hearts, that’s exactly what’s happening.”