JUDY WOODRUFF: And we are joined now by the man tasked with protecting the country from future terrorist attacks, among other things.

As secretary of homeland security, Jeh Johnson oversees some 240,000 workers, spread across 22 government agencies. In addition to counterterrorism, he's responsible for everything from border security, to immigration and customs enforcement, to natural disasters.

Secretary Johnson, we welcome you back to the NewsHour.

JEH JOHNSON, Secretary of Homeland Security: Thank you, Judy. Good to be here.

JUDY WOODRUFF: So we're now 12-and-a-half years past 9/11. How much safer is the United States today than it was then?

JEH JOHNSON: Well, I think we have come a long way since 9/11, which happens to be my birthday, so I remember the day well. I'm a New Yorker. I was in Manhattan on September 11, 2001.

We have come a long way in terms of our counterterrorism efforts. I think we have learned how to do a pretty good job at detecting a number of terrorist threats to the homeland. But we have to be vigilant in a number of respects.

Al-Qaida is now a much more decentralized entity, with affiliates. And we have to always be vigilant in terms of potential homegrown threats, the so-called lone wolf. And we saw an example of that with the Boston Marathon bombing last year.

So we have got to be vigilant on a number of fronts. I still believe that counterterrorism needs to be the cornerstone of the Department of Homeland Security's mission.

JUDY WOODRUFF: So, how much of the threats that worry you now are homegrown? What percentage or proportion are homegrown, and what proportion are external?

JEH JOHNSON: Well, I would hesitate to try to quantify it.

But I think that the potential for homegrown terrorist attacks is something that we have to be very concerned about, because, in many respects, it's harder to detect when you have an independent actor who may be living in our midst, in our own communities.

And so it's one of the reasons I spend a lot of time working with state and local law enforcement, talking to sheriffs, police chiefs, like I did as recently as two days ago. They're the first-responders. And so we spend a lot of time in the Department of Homeland Security working with them, training, grants, preparedness grants, and so forth, because we are concerned about the homegrown terrorist base — homegrown domestic base threat, in addition to the potential threats from overseas.

JUDY WOODRUFF: But it sounds like you're saying you feel more comfortable about that than you — than would have been the case a few years ago?

JEH JOHNSON: I think we have come a long way in terms of our ability to detect potential terrorist attacks in our counterterrorism efforts across the entirety of the U.S. government. But we have got to stay vigilant.

JUDY WOODRUFF: Let me ask you about some of the other issues that you have to work on every day.

One is immigration. While you wait for the Congress to decide what it's going to do one way or another about the question of immigration reform, we know the administration is looking at overhauling some aspects of your deportation policy, including undoing a program that really began in the Bush administration that targets undocumented immigrants who have been found guilty of only minor offenses and who have no prior criminal record other than that.

Why is this particular policy something that deserves to be, that should be overhauled or done away with?

JEH JOHNSON: Well, you're correct that we are evaluating our current enforcement priorities. That's something the president announced that he had asked me to do on March 13. I have been looking at this since I took office in late December.

Part of that, I believe, is taking a fresh look at the Secure Communities program, which is what you referred to a moment ago. In my judgment, Secure Communities should be an efficient way to work with state and local law enforcement to reach the removal priorities that we have, those who are convicted of something.

The program has become very controversial. And I told a group of sheriffs and chiefs that I met with a couple days ago that I thought we needed a fresh start. And this is a conversation I have been having with a number of mayors and governors.

JUDY WOODRUFF: So could that happen in the near term?

JEH JOHNSON: I believe it — I believe it will and it should.

JUDY WOODRUFF: Can you give — say when?

JEH JOHNSON: We're in the midst of evaluating potential revisions to our policies right now. I have been having meetings as recently as today.

JUDY WOODRUFF: I asked you because, of course, groups that are advocating for immigration reform and doing something about deportation have been raising a lot of questions.

There's another issue that immigration advocates, immigration reform advocates have focused on, and that is the so-called Deferred Action program that — where currently, as you know very well, this is a program that protects children who were brought in by parents illegally.

JEH JOHNSON: Yes.

JUDY WOODRUFF: These pro-reform groups want to expand that to the parents, to the families of these children. Is this something the administration is looking seriously at?

JEH JOHNSON: We're looking at a wide variety of things.

And I have talked to a number of individuals, concerned groups about the potential for expanding the DACA program, revising our removal priorities. And I would say that we have to be careful not to preempt Congress in certain areas.

They are the lawmakers. Whatever we do in the executive branch, we have to do within the confines of existing law. So we have a fair amount of discretion when it comes to how we prioritize our enforcement activities.

And, two years ago, the administration developed the DACA program, which I think is a program that has been very effective. And…

JUDY WOODRUFF: This is for the children, only up to age 30.

JEH JOHNSON: This is for the children, correct.

JUDY WOODRUFF: Which — it sounds like you are saying, though, this is less likely to happen than what we were just discussing about…

JEH JOHNSON: I'm still in the midst of my review.

JUDY WOODRUFF: All right.

Well, let me — let me turn around, because, meanwhile, while you are getting this kind of pressure from immigration reform advocates, there are those at the other side of the spectrum who think the administration hasn't done a good enough job with deportations, says you haven't been bringing enough cases to court, and they're critical from the other direction.

What do you say to them?

JEH JOHNSON: Well, first of all, I have learned from my Department of Defense experience that, when we're evaluating important reforms like this, we need to talk to people across the spectrum who have a variety of different opinions. And that's what I am doing.

So, I have spoken to those who are in the category you just described. And I have spoken to those who are advocating change. And I hope that whatever we do reflects a balanced, thoughtful approach that encompasses all these points of view you referred to.

JUDY WOODRUFF: And, finally, Secretary Johnson, I wanted to ask you about — a question about border security.

Our public media colleagues at NPR have done a series of reports in the last few months looking at border security, whether there is a pattern of unnecessary use of deadly or excessive force. We know there's been an investigation.

Is this — do you — you have obviously looked at this. Do you believe the Border Patrol has used excessive force in a pattern that needs to be revamped, so that the policy needs to be revamped?

JEH JOHNSON: I have been now — in six months, I have been to the south border three times.

And I have spoken to our Border Patrol people on the front lines. I think they do a terrific job every single day. I have spoken to the chief of the Border Patrol. And what he and I decided we should do is make our use-of-force policies more transparent. And the chief has modified those use-of-force policies to deal more explicitly with incidents like rock-throwing, for example.

That change was made about two months ago. And I think it was greeted with a pretty positive reaction. So, I think we're in a better place.

JUDY WOODRUFF: So, that's it for now in terms of revamping policy?

JEH JOHNSON: We're always continually evaluating whether we should revamp policy. I think the change we made about two months ago has been, I think, positively received.

JUDY WOODRUFF: The secretary of homeland security, Jeh Johnson, we thank you for joining us.

JEH JOHNSON: Thank you very much, Judy.