brussels u.s. president donald trump defense secretary thursday say see possible military collaboration russia blow moscow hop mend tie washington trump election remark perhaps strong indication yet trump administration prospect significant cooperation u.s. russian militaries islamic state syria unlikely anytime soon come despite repeat suggestions trump election campaign possibility joint action islamic state militants position right collaborate military level political leaders engage try find common grind jim mattis tell reporters talk nato headquarter brussels also mention u.s. concern russian interference democratic elections hours mattis speak russian president vladimir putin say interest nations restore communications intelligence agencies absolutely clear area counter-terrorism relevant governments international group work together tell russia federal security service fsb u.s. intelligence agencies however among powerful voice caution washington russia conclude moscow hack leak democratic party email presidential campaign part efforts tilt vote nov. election trump favor monday resignation national security adviser michael flynn see moscow lead advocate warm tie russia underscore kremlin difficulties reach settlement flynn resign disclosures discuss u.s. sanction russia russian ambassador unite state trump take office late mislead vice president mike pence conversations ask whether believe russia interfere u.s. presidential elections mattis say right would say little doubt either interfere attempt interfere number elections democracies explicitly cite u.s. election kremlin aide say progress potential meet trump putin agreement meet clear understand yet interfax news agency quote kremlin aide yuri ushakov say back-and-forth mattis previously accuse russia try break nato alliance tell closed-door session nato wednesday need realistic chance restore cooperative relationship moscow cite moscow 2014 annexation crimea ukraine plunge u.s.-russia relations post-cold war low mattis say nato need negotiate position strength call step military spend prompt terse reply russia defense minister sergei shoigu attempt build dialogue russia position strength would futile quote say tass news agency mattis shoot back need respond russian statement nato always stand military strength protection democracies freedoms intend pass children back-and-forth come even u.s. secretary state rex tillerson russian foreign minister sergei lavrov meet germany u.s. marine general joseph dunford top u.s. military officer meet chief russian general staff valery gerasimov azerbaijan lavrov dismiss uproar u.s. election know interfere domestic matter countries say congressional inquiries allege russian interference u.s. elections gain momentum capitol hill investigators press intelligence law enforcement agencies access classify document fbi several u.s. intelligence agencies investigate russian espionage operations unite state also look contact russia russian intelligence officer others tie putin government people connect trump campaign trump 's defense chief see military collaboration russia