On Monday, Donald Trump issued one of his most provocative proposals to date: Halt the immigration of all Muslims to the United States.

It was the latest in a series of eye-catching comments — including his vow last week to target the family members of terrorists — designed to show that he’s willing to go to greater lengths than any other candidate to stop terrorism. And it came just hours before the businessman was scheduled to take to the deck of the USS Yorktown in South Carolina on Monday night. Muslim extremism is “going to get worse and worse. You’re going to have more World Trade Centers,” Trump said. 

In the aftermath of terror attacks in Paris and California, Republican voters are applying their toughness test, and, for now at least, polls show that Trump is passing with flying colors.

While Trump — until recently better known for his reality television show than his foreign policy views — lacks the credentials of a traditional national security candidate, the tough-talking businessman’s national support has grown considerably since terrorists killed 130 people in Paris in mid-November. In a CNN poll released last week, registered Republicans named him as the best candidate to handle ISIL and foreign policy by large margins.

Trump’s success, according to Republican strategists, stems from the unmistakable stylistic contrast he strikes with Barack Obama. While the president has projected cool calm in response to recent attacks, Trump has mirrored the two-fisted anger and anxiety felt by many voters. He has warned against accepting Syrian refugees, entertained a national database of all Muslims, said he would target the families of terrorists and now called for the indefinite cessation of Muslim immigration to the United States. 

“What’s driving the ballot in the Republican primary is desire amongst Republican voters for a strong leader. The next president is almost always a reaction to the last president,” said Republican strategist Steve Schmidt, a former adviser to decorated Vietnam veteran John McCain. “When Republican voters look at Obama they see weakness, fecklessness and indecisiveness, and Trump is, in their estimation, the antidote to that.”

Bruce Haynes, president of bipartisan political communications firm Purple Strategies, put it this way: “The power in politics lies in contrast, and when there’s a perception in politics that things are not going very well, people tend to want the opposite. The campaign and the persona of Trump is the polar opposite of Barack Obama.”

Trump’s camp encouraged the contrast with Obama.

“There’s a sharp and definitive difference between the Obama lack of leadership and Mr. Trump’s leadership abilities, and I think the people of this country are ready for a leader to be our president,” said campaign manager Corey Lewandowski.

Most of Trump’s rivals were quick to dismiss his proposal to keep all Muslims from the country as outrageous and fundamentally unserious. 

“Donald Trump is unhinged,” said Jeb Bush on Twitter. “His ‘policy’ proposals are not serious.”

New Jersey Gov. Chris Christie called Trump’s statement “a ridiculous view” and told radio host Michael Medved that the businessman “doesn’t know what he’s talking about.”

Ohio Gov. John Kasich dismissed the rhetoric as “just more of the outrageous divisiveness that characterizes his every breath and another reason why he is entirely unsuited to lead the United States.”

But to a certain type of Republican, looking to register a protest, Trump’s very outrageousness is proof that he’s not part of the system. And that’s more important to many voters than conventional foreign policy or military credentials.

That includes the attendees of Monday’s rally in South Carolina, where Trump read aloud his statement — verbatim but for the added profanity — calling for a freeze on Muslims entering the country. “Donald J. Trump is calling for a total and complete shutdown of Muslims entering the United States until our country's representatives can figure out what the hell is going on,” he said to loud cheers from his supporters. 

“We have no choice. We have no choice. We have no choice,” he repeated as the cheering continued.

Trump then cited data from the Center for Security Policy — a group that believes there is a secret global campaign against Western civilization and that the candidate described as “respected” — saying, "25 percent of those polled agreed that violence against Americans here in the United States is justified as a part of the global jihad.” That statistic was greeted with loud boos from Trump’s supporters.

“They want to change your religion,” said Trump. “I don’t think so. I don’t think so. Not going to happen.”

A ban on Muslims entering the country was not the only radical proposal Trump offered as a solution to prevent terrorism. He also proposed interfering with the Internet to disrupt recruiting channels for radical groups, which often employ social media. He described the proposed measure as “closing that Internet up in some way.”

Trump then repeated his call to renew surveillance of Muslim houses of worship. “Yes we have to look at mosques and we have to respect mosques,” he said. “But yes, we have to look at mosques because something is happening.” 

He told his supporters to report suspicious behavior and not to fear being accused of racial profiling. “I promise I will defend you from profiling. I promise,” he said.

Trump was interrupted several times by protesters, visibly annoying the businessman, who commented during one interruption that lasted longer than he would have liked, “Security is very weak. I can’t believe these security people.”

Trump’s power to overcome biographical shortcomings that would hobble other candidates’ credibility on matters of war and peace became clear at the Family Leader Summit in Iowa in July. There, Trump — who avoided service in Vietnam through student and medical deferments — questioned the war-hero status of McCain, a prisoner of war in Vietnam who refused special treatment from his captors, saying, “I like people who weren’t captured.” After mocking McCain, his support only continued to rise. 

His Monday night rally will be his third on the deck of a decommissioned warship. In September, ahead of the second Republican debate in Los Angles, Trump held a rally hosted by a veterans group aboard the USS Iowa. In October, he held another rally aboard the USS Wisconsin in Norfolk, Virginia. He has pledged to reform the Veterans Administration and often claims that undocumented immigrants receive better treatment in the United States than veterans.

Trump, who attended military boarding school in his youth, also often declares himself to be the most “militaristic” candidate for president, while arguing that he would strengthen the military so much that he would not have to use it because America’s enemies would be intimidated by it. 

The circumstances of last week’s mass shooting in San Bernardino, carried out by a jihadist-inspired immigrant and the son of immigrants, play directly into Trump’s appeal.

“It’s about vision. It’s about someone who understands fundamentally what’s going on and has had the foresight to talk about it for weeks if not months ahead of anybody else,” said Lewandowski.

In making the case for his foreign policy vision, Trump regularly cites his early opposition to the Iraq War and his warning in a 2000 book, in which he mentioned Osama bin Laden by name, that America was vulnerable to a major terrorist attack. “In my book, I predicted terrorism. I can feel it, like I can feel good location in real estate,” he said in Tennessee in November. 

In a primary more defined by national security than many had expected, other candidates have sought to cast themselves as strongest on national security and foreign policy, but none with as much success as Trump. Ted Cruz raised the prospect of carpet bombing large swathes of the Middle East on Saturday in Iowa — where a new poll shows him leading Trump in the first voting state — saying, “I don’t know if sand can glow in the dark, but we’re going to find out!”

Christie has touted his experience as a federal prosecutor on terrorism cases in New Jersey in the wake of 9/11, and Marco Rubio’s experience on the Senate Foreign Relations Committee has bolstered a campaign built in part on his hawkish foreign policy. But according to Schmidt, neither of those credentials elevates those candidates above Trump in the minds of many Republican voters.

“None of [the candidates] have fought in the wars of their generation and none of them have any particular expertise in national security, and a platitude is a platitude, whether it’s offered by a candidate with a political title next to their name or not,” he said. 

In 2012, Mitt Romney’s claim that his business travel gave him relevant foreign affairs experience fell flat in his campaign against a sitting president. But Lewandowski argued that Trump’s experience in international business gives him an edge over his primary rivals. “He does business on five continents around the globe. He’s a recognized expert on international business and has dealt with foreign leaders his entire life. If somebody says that they have experience from sitting in committees in Congress and missing their votes and briefings I don’t know what means for experience,” he said.

Trump has argued that he would succeed on military matters by appointing the “smartest” and “toughest” generals and military advisers, saying that he would look for the likes of Gens. George Patton and Douglas MacArthur.

His supporters have digested that message. “Abraham Lincoln didn’t have any military experience,” said conservative New Hampshire activist Jerry Delemus, a member of the Trump campaign’s New Hampshire veterans committee. “The reality is that Donald Trump is a skilled manager and executive. He knows how to put the right people in there to accomplish the ends he wants to accomplish.”