What makes Donald Trump different from other Republican presidential candidates, which fuels his popularity?

As far as the Vox news outlet is concerned, the answer is that Trump is the only GOP candidate bold enough to say "the things that mainstream Republicans hint at but are too afraid to say explicitly."

Vox recalled an incident last month when Trump told Fox News TV host Bill O'Reilly that he would kill the families of suspected terrorists to deter them from attacking America. "When you get these terrorists," Trump said, "you have to take out their families."

O'Reilly asked Trump if he meant what he said. Trump replied, "I would do pretty severe stuff" — and the crowd watching him roared their approval, Vox said.

Like Trump, other Republican candidates have been focusing on the clear and present danger posed on America and the world by radical Islam in the form of the Islamic State (ISIS).

Most of the candidates agree that the only solution to end the ISIS threat is the use of overwhelming military force.

"Radical Islamic terrorists have declared war on the Western world. Their aim is our total destruction," Jeb Bush said. "We have but one choice: to defeat it."

"There is a war against ISIS, not just against ISIS but against radical jihadist terrorists. That is a war they win or we win," Marco Rubio said during the last GOP presidential debate.

Chris Christie even called the looming confrontation as "World War III."

However, despite their fiery rhetoric, most of the candidates could only offer modest proposals in combating ISIS, which only expand on President Barack Obama's current strategy and do not include the deployment of major U.S. ground forces, Vox noted.

Senator Ted Cruz did propose to "carpet-bomb" areas controlled by ISIS. But when CNN's Wolf Blitzer asked him if he would really carpet-bomb civilian areas, thus intentionally killing many innocent Syrians, Cruz backed off.

"You would carpet-bomb where ISIS is. The location of the troops. You use directed air power. But the object isn't to level a city, the object is to kill the ISIS terrorists," he said.

His remarks showed that Cruz wasn't willing to murder civilians to get at ISIS, Vox said.

In contrast, Trump has no such qualms, which endears him to Republican voters who really do think that ISIS poses an imminent and existential threat to America, Vox said.

The voters see Trump's proposed policy as commensurate to the threat posed by ISIS, viewing his "angry rhetoric as refreshing honesty."

As one supporter said, Trump says "whatever he wants to say without having someone buffer it for him. We like raw truth."