Father of Slain Army Officer Humayun Khan Hits Trail for Hillary Clinton

— -- Khizr Khan, the father of slain U.S. Army Capt. Humayun Khan, who died while serving in the 2004 Iraq War, hit the campaign trail this afternoon for the first time in support of Democratic presidential nominee Hillary Clinton.

"He has made us the laughing stock in this world," Khan said of Republican presidential candidate Donald Trump, whom he first attacked in a speech at the Democratic National Convention in July.

With a copy of the U.S. Constitution in his hand, Khan captivated the nation three months ago when he denounced Trump for his proposal to temporarily ban Muslims from entering the country and telling the GOP nominee, “you have sacrificed nothing.”

At the Masjid William Salaam mosque in Norfolk, Va., home to the world’s largest naval base, Khan said he felt compelled to speak at the Democratic Convention in response to the proposed ban.

"There comes a time in an ordinary citizen's life when you stand up against tyranny, against un-American hate," Khan said. "Would I do it all over again? A million times again, again, again, again, up until this hatred, and bigotry, and political rhetoric in the United States is wiped away."

Khan’s remarks come amidst a day of campaigning for Clinton, where he is meeting with community leaders, volunteers, veterans and military families.

"This city is the most appropriate city to utter these words. I say it with complete comprehension: Donald Trump as a candidate has proven himself temperamentally unfit to be the commander of chief of this great nation," Khan said.

The public appearance comes on the heels of the release last week of an emotional 60-second campaign advertisement for Clinton featuring Khan. He shared the story of his son’s death and asked Trump, “Would my son have a place in your America?”

This afternoon, the Gold Star father went a step further, criticizing Trump’s temperament, saying he shouldn't have any access to nuclear launch codes.

"Once a rocket is launched you cannot take it back," Khan said. “[Trump is] unable to understand, unable to learn the consequences of such a mistake. This person has shown he is apprentice of the nuclear arsenal."

In a later moment of visible emotion, Khan described receiving letters from children who were scared their family was going to be deported and spoke of other immigrants who have faced heavy vitriol from the Trump campaign: the country’s Hispanic and Latino communities.

Khan also hit back at Trump for claiming that his son Capt. Khan would still be alive if he was president.

"This is the most cruel thing you can say to grieving parents, that if I was there this would not have happened,” Khan told ABC News today in response to Trump's comments. “There's no sincerity in those remarks…This is one character that a leader must have to be the leader of a great country, to be the commander-in-chief of the Armed Forces of the United States: empathy. And this person totally lacks that.”

Before leaving, Khan took part in a prayer at the mosque lead by a military member in fatigues and attempted to reach out to voters of all parties.

"I urge all independents. All Republicans. All Republicans are as patriotic as anyone else… to vote for Hillary Clinton."

"I voted yesterday," Khan said.