Republican presidential candidate Donald Trump has called for a "total and complete shutdown of Muslims entering the United States".
The proposed ban would stand "until our country's representatives can figure out what is going on", his campaign said in a statement on Monday.
The statement added that Trump's proposal comes in response to the level of hatred among "large segments of the Muslim population" towards Americans.
"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," Trump said in the statement.
He added on Twitter: "Just put out a very important policy statement on the extraordinary influx of hatred & danger coming into our country. We must be vigilant!"
Trump campaign manager Corey Lewandowski said Trump's proposed ban would apply to "everybody", including Muslims seeking immigration visas as well as tourists seeking to enter the country.
He did not respond to questions about whether it would also include Muslims who are US citizens and travel outside of the country, or how a determination of someone's religion might be made by customs and border officials.
In response to a request for additional detail, Trump said via a campaign spokeswoman: "Because I am so politically correct, I would never be the one to say. You figure it out!"
Trump's proposal comes a day after President Barack Obama spoke to the nation from the Oval Office in the wake of the shootings in San Bernardino, California, which Obama said was "an act of terrorism designed to kill innocent people".
Trump's call goes against US values and would hurt national security, White House deputy national security adviser Ben Rhodes said.
"It's totally contrary to our values as Americans. We have in our Bill of Rights respect for the freedom of religion," Rhodes said in an interview on CNN on Monday.
"It's also contrary to our security," Rhodes said, explaining Islamic State militants were trying to cast the United States as being at war with Islam.
