Malala Yousafzai has been critical of Donald Trump before, but after the new president ordered "new vetting measures" to change refugee policies Friday she issued a statement expressing her extreme sadness and disappointment.

Yousafzai, a Pakistani activist, Nobel Laureate and gun violence survivor, repeatedly shared how "heartbroken" she was about the decision that will impact families fleeing violence and war. She wrote about those coming from Syria, who have been blocked from the U.S. indefinitely and others from Iran, Iraq, Sudan, Libya, Somalia and Yemen, who will be barred from obtaining visas for 30 days.

In the statement, she wrote about a friend who received a visa to the U.S. after fleeing wars in Somalia, Yemen and Egypt and is now a high school graduate in college studying to be a human rights lawyer.

Yousafzai said suspending the refugee program is "closing the door on children, mothers and fathers fleeing violence and war."

She commented on the country's history of accepting refugees and immigrants. "America is turning its back on a proud history of welcoming refugees and immigrants — the people who helped build your country," she wrote.

Read Malala Yousafzai's statement on President Trump's executive order on refugees: https://t.co/KLx5zGU78r pic.twitter.com/hpqNvy90hX — Malala Fund (@MalalaFund) January 27, 2017

Facebook CEO Mark Zuckerberg also posted Friday a strong critique of Trump's new executive order on refugee policy, writing, "We need to keep this country safe, but we should do that by focusing on people who actually pose a threat."

After Trump signed the executive action at the Pentagon (where he swore in Defense Secretary James Mattis) to change refugee policies affecting refugees from Muslim countries, he said, "I'm establishing new vetting measures to keep radical Islamic terrorists out of the United States of America. We don't want 'em here."

The Associated Press contributed reporting.