The mother of a U.S. Muslim soldier who was killed in Iraq castigated Republican Donald Trump on Sunday as ignorant of Islam and of sacrifice after he questioned her silence during her husband's speech at the Democratic National Convention.

Ghazala Khan, whose son, U.S. Army Capt. Humayun Khan, was killed by a suicide bomber in Iraq in 2004, bristled at Trump's implication she was silent because she, as a Muslim woman, had not been allowed to speak.

Khizr Khan, father of slain U.S. Army Capt. Humayun Khan, holds up a copy of the U.S. Constitution as his wife, Ghazala, listens during the final day of the Democratic National Convention in Philadelphia on July 28. (J. Scott Applewhite/Associated Press)

Trump speculated in an ABC News interview, with excerpts posted on Saturday, that she remained silent during the event last Thursday because, "maybe she wasn't allowed to have anything to say."

The following day during an interview with MSNBC, Ghazala Khan said she didn't speak because she's still overwhelmed with grief.

"When Donald Trump is talking about Islam, he is ignorant," she wrote in a Washington Post opinion piece appearing online Sunday. "Donald Trump said he has made a lot of sacrifices. He doesn't know what the word sacrifice means."

Her husband, Khizr Khan, also weighed in after Trump's response. He said he appreciates that Trump called his son a hero, but he finds the Republican presidential nominee "disingenuous" because of his policies and his rhetoric.

Speaking on NBC's Meet the Press on Sunday, Khan said Trump showed disrespect toward his wife and that the country needs to be run by someone with a "moral compass."

'This is why I showed him that constitution. Had he read that he would know what status a Gold Star mother holds in his nation," says Khizr Khan 1:05

On Sunday, Hillary Clinton defended the Khans, saying Trump has a "total misunderstanding" of American values and has inflamed divisions in American society.

Clinton told parishioners in a Cleveland church that Trump's character is questionable because he repaid a family that made the "ultimate sacrifice" with "nothing but insults" and "degrading comments about Muslims."

Clinton said: "I do tremble before those who would scapegoat other Americans, who would insult people because of their religion, their ethnicity their disability. That's just not how I was raised."

Captain Khan and his family represent the best of America, and we salute them. <a href="https://t.co/MGeJXPF2DE">pic.twitter.com/MGeJXPF2DE</a> —@HillaryClinton

Top Republican lawmakers House Speaker Paul Ryan and Senate Majority Leader Mitch McConnell also condemned Trump's remarks in separate statements, although they did not mention their presidential candidate by name.

"Many Muslim Americans have served valiantly in our military, and made the ultimate sacrifice. Capt. Khan was one such brave example," Ryan said. "His sacrifice — and that of Khizr and Ghazala Khan - should always be honoured. Period." he said.

On Twitter, Republican strategist Ana Navarro called Trump's comments about the Khans "gross" and labeled him a "jerk."

Just when I think, Trump can't possibly be a bigger jerk, he proves me wrong. Picking on Cpt. Khan's mom is gross. <a href="https://t.co/9YIhP5XAgQ">https://t.co/9YIhP5XAgQ</a> —@ananavarro

Trump defended himself on Twitter, saying he had been "viciously attacked" by Khan at the convention.

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! —@realDonaldTrump

Captain Khan, killed 12 years ago, was a hero, but this is about RADICAL ISLAMIC TERROR and the weakness of our "leaders" to eradicate it! —@realDonaldTrump

Trump's campaign manager, Paul Manafort, said he sympathizes with the Khan family but that their loss is not the issue at hand. "The issue really is radical Islamic jihad and the risk to the American homeland," he said on CBS, defending Trump's proposal to suspend immigration from some geographic regions.

Trump's take on Crimea

In the interview for ABC's This Week, Trump also said he would consider recognizing Russia's annexation of Crimea, carried out in 2014, if it would lead to better relations with Moscow and stronger co-operation in fighting Islamic State in Iraq and Syria militants.

"I'm gonna take a look at it," he told host George Stephanopoulos in the Sunday broadcast.

Trump also suggested the people of Crimea would rather be part of Russia. That runs counter to the Obama administration, which imposed economic sanctions against Russia for annexing the territory in Ukraine two years ago.

Donald Trump's proposal to suspend all Muslim immigration until the U.S. can 'figure out what is going on,' was made last December. More recently, he has promised to suspend immigration from any country deemed 'compromised by terrorism.' (David Zalubowski/Associated Press)

The United Nations doesn't want countries to recognize Crimea as part of Russia, and some top Republicans are staunchly defending Crimea against what they say is Russian aggression.

When Stephanopoulos mentioned Russia's annexation, Trump said: "You know me pretty well. I don't bow," before mentioning Russia's role in the campaign against ISIS.

"But if we can have a good relationship with Russia and if Russia would help us get rid of ISIS, frankly, as far as I'm concerned, you're talking about tremendous amounts of money and lives and everything else, that would be a positive thing, not a negative thing," Trump said.

"The people of Crimea, from what I've heard, would rather be with Russia than where they were," he said.​