Several U.S. presidential candidates focused on the deadly terrorist attacks in Paris Friday as they made the rounds on television talk shows Sunday morning. Providing their own visions of what the country’s next move should be in dealing with terrorism and the reasons for the expansion of the Islamic State group in recent years were retired Dr. Ben Carson, former Florida Gov. Jeb Bush and U.S. Sens. Lindsey Graham of South Carolina and Marco Rubio of Florida on the Republican side, as well as Sen. Bernie Sanders of Vermont on the Democratic side.

Ben Carson

Republican presidential front-runner Carson appeared to have difficulty expressing a detailed plan to combat the militant group formerly known as either ISIL or ISIS while on “Fox News Sunday.” The candidate, who has come under fire for his comparative lack of experience in foreign policy, said that in light of the terrorist attacks in Paris, the U.S. should no longer accept Syrian refugees. “Bringing people into this country from that area of the world I think is a huge mistake,” he said, arguing that doing so would require a “suspension of intellect.”

In answering a question about the possible deployment of ground troops in Syria to fight the Islamic State group, Carson refused to commit to a number, stating that there already were some boots on the ground. He acknowledged that his lack of foreign-policy experience meant he would need input from military experts.

Carson also said he would be willing to shoot down a Russian plane in the event it violated a no-fly zone in Syria, despite the danger of retaliation by Russian forces. “If they violate it,” he said, “we will, in fact, enforce it. We’ll see what happens. For us to always be backing down because we’re afraid of a conflict, that’s not how we became a great nation.”

Marco Rubio

Rubio advocated that Article 5 of the Washington Treaty be invoked and discussed his views of the phrase “radical Islam” during an appearance on ABC News’ “This Week.” Article 5 is the section of the NATO agreement that provides for collective defense, stating that an attack on one NATO country represents an attack on all NATO countries, with alliance members obligated to assist the nation under attack.

When asked what he believed President Barack Obama should be doing right now, Rubio replied: “First, I would ask our allies to invoke Article 5. This is clearly an act of war and an attack on one of our NATO allies, and we should ... bring everyone together to put together a coalition to confront this challenge.”

Rubio also argued that terrorism by members of extremist organizations such as the Islamic State group are “motivated by their faith.” He added: “Of course, not all Muslims are members of violent jihadist groups, but there is a global jihadist movement in the world, motivated by their interpretation of Islam ... This is not a geopolitical movement. It’s a religiously oriented movement.”

Bernie Sanders

The independent Sanders elaborated on remarks he made during the Democratic presidential candidates’ debate Saturday about climate change propagating terrorism while on CBS News’ “Face the Nation.” According to Sanders: “When you have drought, when people can’t grow their crops, they migrate into cities. When they migrate into cities, they don’t have jobs. There’s going to be a lot more instability.”

Sanders was doubling down on a claim he made during the debate, when he said that what happened in Paris was an early manifestation of the effects of climate change on terrorist activity.

Jeb Bush

Bush discussed Paris, Syria and the role the U.S. should play moving forward during appearances on CNN’s “State of the Union” and NBC News’ “Meet the Press.”

On CNN, Bush emphasized the need for the U.S. to take a leading role in the fight against the Islamic State group and to have a strategy while doing it. He stopped short of saying the U.S. should not accept Syrian refugees, but he did say the country “should focus [its] efforts as it relates to refugees for the Christians that are being slaughtered.” He also said Obama “should convene the North American Council to [decide whether NATO should declare war on the Islamic State group].”

On NBC, Bush said most Syria refugees should be kept in their own country, albeit in to-be-established “safe zones.” He also said, “We should declare war and harness all of the power the U.S. can bring to bear, both diplomatic and military, of course, to be able to take out ISIS.”

Lindsey Graham

Graham, who is considered a long shot for his party’s nomination and is polling near the bottom of the field, said, “Obama’s strategy against ISIL isn’t working,” while on CNN’s “State of the Union.” He added: “We don’t have until the next election to deal with ISIL. There is a 9/11 coming, and it’s coming from Syria if we don’t disrupt their operations inside of Syria.”

Graham reiterated that remark several times, saying: “What you see in Paris is coming to America, and if I’m commander in chief, it will not happen, I promise you.” He advocated putting 10,000 American troop in Iraq, rather than 3,500, and is the only Republican candidate other than former Sen. Rick Santorum of Pennsylvania who is advocating a ground war in Syria and Iraq with a specific number of troops.