Amid rising public anxiety over terrorism, presidential candidates Hillary Clinton and Donald Trump have tried to portray themselves as tough on national security.
For Trump, the Republican nominee, that means being firm on immigration, a hot-button campaign issue that has expanded to dominate the debate over terrorism.
Trump is no longer hawking a controversial proposal he announced after the Paris terrorist attacks last November to ban Muslims from entering the country.
Instead, he talks about “extreme vetting” of immigrants from Muslim nations to keep terrorists out of the country.
He also opposes admitting refugees from the Syrian conflict, warning that Clinton’s plan for escalating their numbers to 65,000 could unleash a "Trojan horse" of terrorists on the American homeland.
"Wait till you see what happens in the coming years," Trump said ominously during the final presidential debate last week.
Clinton, the Democratic contender, has condemned Trump’s call for a prohibition against Muslims entering the country but her plan supports "rigorous screening" of refugees from Syria and elsewhere.
"I will not let anyone into our country that I think poses a risk to us," she said during the second presidential debate.
But now that Trump is no longer promoting his Muslim ban, “there may not be quite as huge of a difference as some people think” between the two candidates, said Michael O’Hanlon, a senior fellow at the Brookings Institution in Washington.
Republican U.S. presidential nominee Donald Trump (R) and vice presidential candidate Mike Pence (L) hold a campaign rally in Cleveland, Oct. 22, 2016.
Protecting the homeland
With fears of homegrown terrorism on the rise, both candidates have called for efforts to stop Muslim radicalization at home.
Trump says he wants to establish a “Commission on Radical Islam” to “expose the networks in our society that support radicalization.”
Trump, whose anti-Muslim rhetoric has been blamed for an increase in hate crime targeting Muslim Americans, acknowledged during last week’s debate that Islamophobia was a problem. But he told a Muslim American questioner: “Muslims have to report the problems when they see them. If they don’t do that, it’s a very difficult situation for our country.”
Clinton sees the Democratic-leaning Muslim American community as critical to safeguarding the country against homegrown terrorism and has met with its leaders during the campaign.
"These Americans may be our first, last and best defense against homegrown radicalization and terrorism," she said last December.
Among other things, her "Comprehensive Plan to Defeat ISIS and the Threat of Radical Jihadism" calls for an "intelligence surge" to give law enforcement the edge in detecting and disrupting terrorist plots and a "lone wolf task force" to identify and stop radicalized individuals.
Fighting the Islamic State
To defeat the Islamic State, Clinton and Trump both have advocated working with a coalition of European and Middle Eastern nations, using drones and special operations forces against Islamic State targets in Iraq and Syria, and establishing a no-fly zone over northern Syria.
But they disagree over other issues. Among them: Clinton wants to arm Syrian rebels fighting the regime of President Bashar al-Assad, something Trump opposes. On the other hand, Trump favors putting more boots on the ground. Clinton has said she's against the idea of sending ground troops.
FILE - In this undated file photo released by a militant website, which has been verified and is consistent with other AP reporting, militants of the Islamic State group hold up their weapons and wave flags on their vehicles in a convoy.
O’Hanlon said that both Clinton and Trump "think they need to do a little more than Barack Obama" but "neither one wants a big military intervention."
But Max Abrahms, a terrorism scholar, argues that the two candidates' differences are in fact deeper than many assume and that they stem from how each views the phenomenon of terrorism.
Clinton subscribes to the "grievance model" of terrorism, the notion that terrorism is inspired by a sense of injustice, said Abrams, a political science professor at Northeastern University in Boston.
Trump, by contrast, leans toward the "opportunity model," so named for the view that terrorism thrives in conditions where there is a greater opportunity for its growth, he said.
To Abrahms and other critics, Clinton is a neocon, a foreign policy hawk who favors the use of force to topple undemocratic regimes and establish democracies in their places.
"For every single regime change – Iraq, Syria and Libya – Hillary has been a much, much bigger proponent than Donald Trump of regime change," Abrahms said.
But O’Hanlon rejects the notion that Clinton subscribes to the doctrine of "regime change” as a tool of American foreign policy.
“It was never something Hillary was super enthusiastic about even when she voted for the Iraq war,” O’Hanlon said, adding that though she supported the removal of Libyan dictator Muammar Ghaddafi, she was not as eager about the overthrow of Egyptian strongman Hosni Mubarak.
For his part, Trump blames Clinton’s apparent penchant for “nation building and regime change” for sowing instability in the broader Middle East. He has gone so far as to claim that Clinton and Obama “founded” the Islamic State group.
Clinton has expressed regret over her vote endorsing the 2003 U.S. invasion of Iraq but she continues to defend her support for U.S. military intervention in Libya in 2011.
Questioned about Trump’s contention that her decisions led to instability, she said in November that “it is not at all clear what the final outcome will be" in these countries.
The Middle East may have been far from an oasis of stability before 2009, but “I think many policymakers would probably trade the current conditions, which border on anarchy in some of these cases, for the dictatorships of what were admittedly some very odious men,” said Colin Clarke, a political scientist at RAND Corp.