Each new revelation about contacts between Russian officials and President Donald Trump's advisers raises more questions and concerns about national security and a foreign nation's interference with U.S. elections. The best way to clear the air and get the facts would be a thorough investigation by the Justice Department, Congress or an independent, bipartisan commission. The American people need to be fully informed, and the Trump administration cannot be successful with such a dark cloud hanging over it.Trump made the correct decision late Monday night to force out national security adviser Michael Flynn after the Washington Post reported Flynn misled Vice President Mike Pence and others by denying he discussed U.S. sanctions against Russia with the Russian ambassador before Trump's inauguration. Flynn lasted just 24 days, and he never should have been hired in the first place. But his departure does not mean it is time to forgive and forget.To borrow a familiar phrase, there remain questions about who knew what when. The FBI started questioning Flynn about his Russian contacts shortly after the inauguration, and the acting attorney general told the White House counsel late last month about Flynn's misleading statements. The White House says Trump was immediately informed. Yet Pence was not told for two weeks while he continued to publicly defend Flynn as being truthful. That was a terrible disservice to the vice president, yet it appears Trump abruptly forced Flynn out not because he lied to the administration but because the lie became public.It gets worse. The New York Times reports Trump's campaign repeatedly was in contact with Russian intelligence officials in the months before November's election. U.S. intelligence agencies discovered the communications as they were investigating the Russian hacking of the Democratic National Committee in an attempt to sabotage Hillary Clinton's campaign and help Trump. This is more alarming than the incoming national security adviser talking to the Russian ambassador, and it needs more scrutiny.Trump and his campaign aides have denied anyone from his campaign knowingly spoke to Russian intelligence agents. Predictably, the president focused Wednesday on defending Flynn, berating the news media and complaining about the anonymous sources who provided the reporters with the information. That is a diversion. If he has nothing to hide, Trump should welcome an independent investigation that would set the record straight and enable him to hit the restart button on an administration that has had a chaotic launch.For months, Trump has expressed his fondness for Russian President Vladimir Putin's leadership. Flynn and some of the president's campaign aides had close relationships in Russia. As a candidate, Trump said he enjoyed reading the hacked Democratic emails that damaged Clinton's campaign. As president, he has watched Russia escalate its activities in Crimea, secretly deploy a missile in violation of a U.S. treaty and buzz a U.S. destroyer in the Black Sea with its planes. Against that backdrop, there should be a sense of urgency to get to the bottom of any and all relationships between Trump or his advisers and the Russians.Senate Majority Leader Mitch McConnell and other Republican senators from Marco Rubio to John McCain have sent encouraging signals that the Senate will take its investigation into Russia's involvement in the election wherever it leads. But the investigations should occur in a different venue than the House and Senate intelligence committees so they can be more open and transparent. Republicans and Democrats should be united in seeking a complete picture and sharing it with the American public.This is an opportunity for Trump to bring order to his erratic approach to foreign policy and national security. He should appoint a competent national security adviser with well-established credentials and widespread respect. And he should welcome an independent investigation into who did what with Russia. That is the only way for the president to rebuild public support, restore confidence among fellow Republicans in Washington and refocus on his priorities.