CNN 2012-04-28（打印版）

First up, the race for the White House rolls on with yesterday's primaries in New York, Pennsylvania, Delaware, Connecticut and Rhode Island. We mentioned yesterday that former Massachusetts Governor Mitt Romney is now the Republican Party's presumptive nominee. It takes 1,144 delegates to officially win that nomination. And even if Governor Romney won every delegate in every primary Tuesday, he wouldn't reach that number. The earliest he could hit the delegate milestone is in late May. Couple other big campaign moment on the horizon: one, the selection of a vice presidential nominee. There's a lot of talk now about whom Governor Romney might pick as his running mate. Two, the national party conventions: that's when Governor Romney and President Obama will officially be named as their party's presidential nominees. For more in-depth coverage on the 2012 election and to check out results from yesterday's primaries, go to the Spotlight section on our homepage and click on the CNN Election Center link.

Today's Shoutout goes out to Ms. M government classes at Rancho High School in Las Vegas, Nevada. What government agency is responsible for safeguarding U.S. borders? You know what to do. Is it the Justice Department, Homeland Security Department, Interior Department or Defense Department? You've got three seconds, go.The Department of Homeland Security is responsible for securing America's borders. That's your answer, and that's your Shoutout.

Our next report today is from Suzanne Kelly, and it's about one specific border, the one between the United States and Mexico. It's patrolled by different agencies that are part of Homeland Security, like Customs and Border Protection, or CBP. The agents use different tools to do their jobs. Sometimes that means using advanced technology. Other times it requires some equine assistance.

The terrain here is really pretty unforgiving. I mean we just came down about a 200-foot drop a few minutes ago. And this tells you what they're up against. Now post 9/11, CBP has taken sort of an all-threats environment stance. That means it doesn't matter whether these groups are people trying to come here illegally, drug runners or potential terrorists. The threats and the environment in which they have to chase them down is just the same.

These guys patrol this area day and night. And they are looking for signs,it's this ancient art of sign cutting, they call it.

What we are looking for is footprints, any impressions, anything in the dirt that would indicate somebody walking through here. So what we do in this case is we always want to look into the sun. We want the to use that sunlight to reflect off the ridges on the ground or the impressions in the ground. And that's going to help define what we are seeing.

This is the Joint Operations Information Center, really, the nerve center for CBP and everything they've got eyes on. They have got eyes on the ground here. They are watching the ports of entry. They have got eyes in the air.And then over here, the guys who watch it 24 hours a day gather all of this information together and figure out what to do next.

That one single human intelligence source was reporting that they were using vehicles in order to beat us on the border.

The terrorism threat is the most important thing the CBP focuses on. It's the greatest threat to our nation. And all agencies and all departments need to be focused on their portion of how to stop that threat.

All right. So now, we are at the Davis Mountain Air Force Base. And we're going to get a very up close look at the aerial assets that the Border Protection uses. What do you need the Black Hawk for along the border.

There are some places that we take them that would take probably 24 hours to get to. Sometimes we have to actually hover on one wheel, when we kind of jump out

If patrolling on horseback is the more traditional approach to keeping a border secure, this is the future. This is a Predator. It's got a 66-foot wingspan, weighs just a touch over 8,000 pounds. But here is the real payoff: it has a $2.5 million camera. It can take pictures day or night. And it's also equipped with an infrared sensor. That's a big deal because it can direct people on the ground exactly to the location of a target.

It is very difficult to seal any part of the border 100 percent guarantees. We don't offer any guarantees in the Border Patrol.

It's on your shoulders, sits the responsibility of making sure there's not another 9/11 in this country.

CNN 2012-04-28（在线收听）