Ban Muslims from entering US, says Donald Trump
And it wasn't just an off-the-cuff remark caught by a hot mic.
In a statement released on Monday by his campaign, Trump called for a "total and complete shutdown" of Muslims entering the US until elected leaders can "figure out what is going on".
"Until we are able to determine and understand this problem and the dangerous threat it poses, our country cannot be the victims of horrendous attacks by people that believe only in Jihad, and have no sense of reason or respect for human life," said the presidential contender's statement.
Trump said that a significant number of Muslims harbour a "hatred" towards America and should not be allowed into the country.
Press sources questioned Trump's campaign on whether his statement included Muslim-Americans who were currently abroad, to which Trump spokeswoman Hope Hicks replied over email: "Mr. Trump says, 'everyone.'"
That presumably includes those taking holiday, or serving in the United States armed forces.
Trump's statement comes only a day after the US President Barack Obama made a speech from the Oval Office in which he urged Americans not to turn against each other in the wake of the attacks in Paris and San Bernardino, California.
In response to Trump's proposal, the White House on Monday said that the call was "totally contrary" to US values.
Last month, UN Secretary-General Ban Ki-moon warned the Security Council of the dangers of reprisals against Muslims in the wake of recent terrorist attacks.
"I am especially concerned about reprisals or further discrimination against Muslims, in particular Muslim refugees and migrants. This would just exacerbate the alienation on which terrorists feed," he told the UN Security Council.
Antonio Guterres, the UN's refugee chief, agreed on Monday.
"When people say they cannot receive Syrian refugees because they are Muslims, those that say it are supporting terrorist organisations and allowing them to be much more effective in the recruitment of people," he told reporters.
"The more it is said, or the more it is done in hostility to Syrian refugees because they are Muslims, the more the chances for [IS] and other groups to recruit people within the borders of European countries to do the kind of nasty things we are now witnessing."
Trump, the billionaire Republican candidate, has made a number of extreme statements against Muslims in recent months, such as calling for surveillance of American mosques and refusing to rule out special IDs and databases for Muslims.
An opinion poll released on Monday showed Donald Trump falling to second place in Iowa in his bid to secure the Republican nomination as presidential candidate behind Ted Cruz.
Observers have suggested a correlation between Trump's faltering poll results and his rabble-rousing designed to drum up support from the Republican Party's extreme far-right base.
Twitter users, on the other hand, warned of the dangers of Trump's rhetoric.