Transcript for Inside US longest war as it rages on in the Afghan mountains

here to an ABC N exclusive. Our series, the newnt in af America's longest war. GHT, our tea trave with U.S. Special forces on T for ISIS. And you're about to see W Ian with American faces on T front lines. And what they discovered Hidde just a few feet . Here ABC's foreign correspondent Ian Pannell. Reporter:t explosi the distance is the work of U.S. Special forces targetin isisn the moins of Afghanistan. Where America's longest war S on tonight. We were given exclusive access in 17 yea R on this war, this was the first time go with the U.S. Army green berets ey checked our footage after trthe dirt RDS that lead to ISIS, all to protect secure on the ground. What youlooking at now is the U.S. Militstriking is ons, ISIS S, try degrade their capacity. Buile they aireriority the truth is Stille to put troops on the groundtake the fight to the militants. Mission is day.as we Joi the U.S. Troops as they go dooro-door, checking for isisighters anhidden bombs. The troops throw in a grenade. To make sure clear. Thtroojust moved into a whole series of compounds, I ot worse tey clear. Ey have co across number of ieds. E arof most deadly tracks in the world. Laced with I every footstep ho be made safe. Every builo be checked. Here we found some bomb part Ie ied,. Reporr:ng the track, our path is blocked. There's a booby-trapped Bo this special forces sergean lls what we'ooking at.ck is a preur is.eporter: H CN is it for Yo to come across this kind of device? Ery time come down to the valley, we've found em so far. Reporter: Too big to dismantle,hede to blow it up. The ground to see what happened next. Thharges Aring be laid. We just had ak at ie experts are moved ba to T charge, the timer's G and nextew seconds, there's to be a veoud bang. Thaas a big O. Reporte you can H the sound of some of thehrapnel coming dn explosion there and T from the GU me that that was obously a vy ce that had laid on E one ied tonated -- have a look at the -- just a couple of steps fromre we were. But these americanighters kw E will beany more othe road ahead. Ia ABC N afanistan. Ours to Ian and T team and we'll stay on meantime,k

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