R4&S – The DoD has a new acronym for the long-running conflict in Afghanistan. R4&S stands for regionalize, realign, reinforce, reconcile, and sustain. The acronym R4&S was revealed during testimony by Secretary of Defense Jim Mattis before the Senate Armed Services Committee on October 3, 2017. 
Regionalize. The U.S. will be looking beyond the borders of Afghanistan to the neighboring countries and other nations in the immediate region to find solutions for ending the conflict. Key countries in this regional approach are Pakistan, Iran, China, and India. India is expected to step up development efforts in Afghanistan while Pakistan needs to stop supporting the Afghan Taliban.
Realign. The U.S., and presumably the NATO and partner nations in the Coalition, will be providing advisors down to tactical level units. For the past few years advisors were limited to Army corps or Police zone HQs units (except for SOF). Now advisors and trainers will be realigned from the corps and institutional level down to Army brigade and battalion (kandak) level units. The Resolute Support headquarters and the several corps level Train, Advise, and Assist Commands (TAACs) will likely deploy an increased number of expeditionary advisory packages (EAPs) to brigade and battalion level. While the Afghans will do the fighting advisors will accompany these tactical units and assist with fire support when needed. SECDEF called it “combat duty” but with the Afghan forces in the lead.
Reinforce. More troops are on the way. Up to 3,000 more U.S. troops are increasing the U.S. force presence in Afghanistan. Fifteen NATO and Coalition partner nations are expected to increase their troop levels as well. The majority of these new troops are expected to extend NATOs advisory effort to Afghan units currently without advisors.
Reconcile. For years the Afghan government has attempted to reconcile and reintegrate low, mid, and high-level insurgents back into Afghan society. This “R” is “. . . the desired outcome from our military operations”. Mattis believes that positive gains on the battlefield will lead to an “Afghan-owned, Afghan-led peace process”. Reconciliation and reintegration hasn’t worked out very well in the past. But let’s try again!
Sustain. We are in for the long haul. We don’t have a time table for withdrawal; it is conditions-based. Mattis says that “War is principally a matter of will.” The message to the insurgents is that the U.S. and the Coalition isn’t leaving Afghanistan any time soon. Supposedly this will put the insurgents on notice that the time to ‘reconcile’ is now.
 See the -1:14 minute mark of the Senate testimony video (part 1) below for SECDEF Mattis’s description of R4&S.
Videos of SECDEF Mattis and General Dunford testimony before the Senate Armed Services Committee, October 3, 2017.