I know this is not my usual position. But this is a war. Therefore I have come to believe there should be no immigration or visa waivers until the U.S. adopts a completely new system to stop radical Islamic terrorists from entering the country. A wartime lockdown. And a big change in my thinking.

ISIS and related Islamic terrorists are already here. More are coming. We must stop them.

Until FBI director James Comey gives us the green light, I say seal the borders.

Here’s what we must do: Completely reform the vetting process for immigrants and foreign visitors. Change the screening process. Come up with a new visa-application review process. Stop this nonsense of marriage-visa fraud. And in the meantime, seal the borders. I agree with Jessica Vaughn, director of policy studies at the Center for Immigration Studies, who argued many of these points in excellent detail on the National Review website on Friday.

Again, why am I taking this hardline position? In the past I have been an immigration reformer, not a restrictionist. But we are at war. That changes everything.

Let me emphasize that my support for wartime immigration restrictions is not based on religion. I think Donald Trump made a big mistake here. Instead, I agree with this Rupert Murdoch tweet: “Complete refugee pause to fix vetting makes sense.”

Fortunately, the Republican House voted to tighten restrictions on travel to the U.S. by citizens of 38 nations who presently enter our country without a visa. This covers 20 million visitors a year who are allowed to stay 90 days. And of course this system is abused, big time.

But I say seal the borders. People hoping to relocate to the U.S. from Syria, Iraq, and anywhere in the Middle East, and people coming here from France, England, Sweden, and wherever will be upset, at least for a while. There may be some unfairness to this. But I don’t care. Wars breed unfairness, just as they breed collateral damage.

We may set back tourism. We may anger Saudi princes whose kids are in American schools. But so be it. We need a wartime footing if we are going to protect the American homeland.

Of course, President Obama doesn’t get it. He never will. Already we should have led NATO into a declaration of war against ISIS. Alreadywe should have pushed a resolution of war against ISIS through the UN Security Council. Already we should have convened meetings with our Mideast allies to formally declare war against ISIS. Already the U.S. Congress should have issued a formal declaration of war against ISIS.

The president had his last chance last Sunday night. And he didn’t do it. He is not a wartime commander in chief. In fact, he is not a commander in chief.

As I have written before, if the U.S. wants to destroy ISIS, it can destroy ISIS. We won’t end terrorism around the world. But we can destroy ISIS in Syria and Iraq. Prominent generals are telling us that. Prominent national-security strategists are telling us that.

So let’s do it.

If there is to be a true wartime effort to destroy ISIS, our leaders must communicate a sense of urgency and energy. Define the clear goal: the destruction of ISIS. Speak to that goal constantly. Take steps at home and abroad to back up that goal. Lead the country. Rally the country.

Republican and Democratic commanders in chief have done this in the past. We must do it again.

I don’t believe a visa or immigration lockdown here in the U.S. will solve the Islamic terrorist threat. Many other steps must be taken. And I am not suggesting this in the name of religious profiling. Instead, I am hardening my position on immigration because we are at war and I fear we may be losing this war.

My shift in thinking comes from a deep desire to strengthen homeland security. Hopefully an immigration freeze will not be in place for very long. But for now I believe we must do it. (By the way, keeping America safe is a prerequisite for growth.)

And let me add, as I have in the past, if the U.S. has the will, the urgency, and the energy to destroy ISIS, then we will destroy ISIS.