The last time Donald Trump had a full-fledged news conference, he urged Russia to find and reveal more of Hillary Clinton's emails. That was in July. Now he's in an unprecedented public battle with all 17 US intelligence agencies, accusing them of "a political witch hunt." He denies Vladimir Putin helped him defeat Clinton -- alarming Republicans as well as Democrats about future Russian relations. How serious is Putin's meddling in US politics? Will Trump's own financial ties to America's powerful antagonist be a risk to national security?