washington lawyers president donald trump former national security adviser michael flynn yet indicate whether flynn plan comply senate intelligence committee subpoena document panel chairman say statement thursday general flynn attorneys yet indicate intentions regard senate intelligence committee subpoena republican senator richard burr say statement burr tell reporters early thursday flynn lawyers say would honor subpoena issue connection committee investigation russia 2016 u.s. presidential election congressional aid tell reuters committee still negotiate hop obtain request document consistent committee position since begin investigation welcome willingness cooperate burr say two-sentence statement trump ex-adviser flynn yet indicate whether honor subpoena senator