Reactions could include federal indictments, sanctions, counterattacks and even exposure of Kremlin corruption, experts say

Tech giant issues call-to-arms after attack on US government institutions blamed on Russia; singles out Israel's private sector, NSO Group as potentially dangerous going forward

'They got into everything,' one official says as federal authorities express growing alarm over breadth and depth of intrusion into government networks, likely by Russian actors

Russian president, one of the last world leaders to wish the US president-elect well, says he hopes the 2 countries can work together 'despite their differences'

Administration seeks to tie hands of president-elect, but many decisions -- including sanctions and West Bank labeling -- can be easily reversed by Biden, or simply go unenforced

Russian holdout allows delay in addressing fraught question of how to improve ties; leaders of China, Brazil, Mexico and Turkey also yet to wish the US president-elect well

Group, not in American custody, targeted French election, Ukraine, Olympics; was behind 'most disruptive and destructive series of computer attacks ever attributed to single group'

Moscow says Washington's 'theatrics do not correspond to reality,' as the White House insists measures against Tehran have snapped back -- in defiance of the rest of the world

In whistleblower complaint, former DHS official alleges he was pushed to alter reports so they'd reflect administration policy goals, was reassigned for refusing to go along

NATO says there's 'proof beyond doubt' that Russian opposition leader was given Novichok; US president says nuclear arms negotiations with Moscow more important than anything