Hemadeacommitmenttothenation'sservicemembers,inarefuelingstopatElmendorfAirForceBaseonhiswaytovisitingfournationsinAsia."IwantyouguystounderstandIwillneverhesitatetouseforcetoprotecttheAmericanpeopleorourvitalinterests.Ialsomakeyouthispromise:IwillnotriskyourlivesunlessitisnecessarytoAmerica'svitalinterests,"hesaid.ThepresidentandhistopadvisershavebeendiscussinghowtoproceedwiththewarinAfghanistan.Mr.Obamatoldthetroopsandtheirfamiliesanyplanhechooseswillincludesufficientsupportforthem."Wewillgiveyouthestrategyandtheclearmissionyoudeserve.Wewillgiveyoutheequipmentandsupportthatyouneedtogetthejobdone,andthatincludespublicsupportbackhome.ThatisapromisethatImaketoyou,"hesaid.ThepresidentdidnotspecificallymentionAfghanistaninhistalktothetroops,butheisexpectedtosendthousandsmoreservicememberstofightthere.AftermeetingwithhisadvisersonWednesday,Mr.Obamaaskedforrevisedoptions.WhiteHousepresssecretaryRobertGibbssaysthepresidentwillnotannouncehisAfghanistanstrategybeforereturningfromAsianextweek.GibbsalsosaysMr.ObamawantsbenchmarksforevaluatingU.S.progressinAfghanistan,andwillnotcommittoanopen-endedconflict.PublicsupportforincreasingtrooplevelsinAfghanistanhasbeeneroding.AnAssociatedPresspollthisweekshowsthat54percentofAmericansopposesendingmoretroops,upfrom50percentinOctober.Thepresident'sAsiatripwilltakehimtoJapan,Singapore,ChinaandSouthKorea.Theglobaleconomy,trade,climatechangeandNorthKorea'snuclearprogramareexpectedtobeamongthetopicscoveredinthevariousmeetings.