by Barbara Slavin

In the year since he announced his candidacy for U.S. president, Donald Trump has insulted Mexicans, war heroes, women, disabled people, the children of immigrants and Muslims. So perhaps no one should have been surprised when he denigrated the parents of an immigrant Muslim American war hero, Army Capt. Humayun Khan, killed by a suicide car bomb in Iraq in 2004 while he was protecting those under his command.

Just a week after accepting the Republican Party’s nomination for president, Trump suggested that Khan’s mother was forced to stand by silently while her husband spoke at the Democratic National Convention.

“His wife, if you look at his wife, she was standing there,” Trump told ABC’s George Stephanopoulos in an interview broadcast on Sunday. “She had nothing to say. She probably — maybe she wasn’t allowed to have anything to say.”

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From “This Week” ABC News Interview with Donald Trump responding to criticism from Gold Star Father Khizr Khan

Trump’s implication was that the Khans’ Muslim faith or Pakistani origin obliged Ghalaza Khan to remain quiet.

Mrs. Khan proved Trump wrong, appearing on television and writing a moving op-ed for The Washington Post.

Trump’s anger at the Khans eclipsed empathy for their loss. Incredibly, the 70-year-old real estate magnate, in the interview with Stephanopoulos, compared the “sacrifices” he said he had made as a businessman to that of the Khans in losing their 27-year-old son.

Once again, it was clear that while Trump is quick to dish out criticism, he sure can’t take it — not the most reassuring quality in someone seeking the most important and heavily scrutinized political office in the world.

Predictably, Trump’s comments blew up the internet and dominated social media for days.

In a manner reminiscent of his inability — after clinching the necessary votes for the Republican nomination — to stop complaining about a judge, Gonzalo Curiel, who Trump alleged was incapable of ruling fairly because of his Mexican parentage, the GOP nominee unleashed a steady stream of statements and tweets about the Khans that only served to underline his thin skin and shaky grasp of democratic rights.

Gold Star father Khizr Khan addresses the Democratic National Convention about Donald Trump July 28, 2016

Khizr Khan, Humayun’s father, had asked at the Democratic convention whether Trump had read the U.S. Constitution and offered to lend him a copy; Trump’s campaign replied in a statement that Khan “has no right to stand in front of millions of people and claim I have never read the Constitution,” thereby proving Khan’s point. The first amendment to the Constitution guarantees freedom of speech, as well as religion, the press and the right to peaceful protest. There are 10 such amendments, collectively known as the Bill of Rights. The Constitution also has seven articles; Trump once referred to a 12th article.

When Khan pressed his critique of Trump in interviews on Sunday, Trump replied in a tweet:

I was viciously attacked by Mr. Khan at the Democratic Convention. Am I not allowed to respond? Hillary voted for the Iraq war, not me!

— Donald J. Trump (@realDonaldTrump) July 31, 2016

There is a legitimate debate that could be had in this campaign about national security. Clinton’s support for the Iraq war and apparent greater readiness to intervene in foreign conflicts than Trump is a topic that needs to be addressed.

When it comes to immigration and a U.S. plan to accept 10,000 refugees this year from Syria – a quota that is unlikely to be met but Clinton has said she would increase fivefold – it is reasonable to review the extensive vetting system already in place and ask if more can be done to weed out potential terrorists.

Strained U.S. relations with Russia are also an important topic that should be raised if and when the Trump and Clinton campaigns can agree on dates for televised debates this fall.

Trump has made no secret of his admiration for Russian leader Vladimir Putin, which appears to stem, in part, from the Trump’s belief that Putin   has said that he likes the brash New Yorker. Or as Trump put it to Stephanopoulos, “just so you understand, he [Putin] said very nice things about me.”

In the interview, Trump appeared not to know that Russia has intervened in the Ukraine to support ethnic separatists in the eastern part of the country. Trump also professed a lack of involvement in changing the platform of the Republican Party to exclude a call for sending weapons to Ukraine to help it defend itself against Russian aggression.

Trump, who has had business ties with Russians for years, has already unnerved U.S.   allies in Europe by demanding that many spend more on defense or risk the United States walking away from its historic commitments under the NATO treaty.

The fury over Trump’s comments about the Khans eclipsed a previous kerfuffle last week over his call on Russian intelligence to find 33,000 emails deleted from Clinton’s private server after she completed her term as secretary of state. Coming on the heels of the release by Wikileaks of emails apparently hacked by Russia from the Democratic National Committee, those remarks raised new concerns about Trump’s credentials among both Republican and Democratic members of the national security and intelligence community.

One hundred days out from the US elections, what bizarre new statements will Trump make and will they determine the fate of his iconoclastic candidacy? Are Americans experiencing so much pain and anxiety that many would vote for such a man?

Barbara Slavin is Acting Director of the Future of Iran Initiative at the Atlantic Council in Washington. Follow her on Twitter @barbaraslavin1