preparing. >> reporter: we're now close to the southern edge of the demilitarized zone, this sign warning against going any further. now, south korea is used to blood-curdling threats from the north. they pretty much take them in their stride. also, in the past when there have been attacks, the south has been reluctant to hit back. but what changed this week is where rockets came from the north thursday, seoul hit back forcefully with a big barrage of its own. they've made clear that this weekend, if there is any prof kags from the north, they will again hit back and they'll hit back hard. ian williams, nbc news, near the dmz. >> i'm joined by former new mexico governor bill richardson. also former u.s. ambassador to the united nations. governor, we've seen these types of threats before from the north. is there any reason to believe it's different this time? >> well, it is different this time. it's the most heightened tension in the last five years.