If congressional Republicans were as concerned about national security today as they claimed to be in the wake of the Benghazi attacks in 2012, subpoenas from investigative committees would be dropping like confetti. Americans deserve to know the precise nature and history of the relationships between key advisers to President Donald Trump and the Russian government.

It shouldn't have come to this, but Michael T. Flynn's resignation Monday as national security adviser should finally embarrass Congress into doing its job. U.S. intelligence agencies reached consensus last fall that Russian computer hackers tried to interfere with the presidential election to tilt the election Trump's way. Some analysts say Russian President Vladimir Putin was personally involved — and jubilant at the result.

Trusting his spies, President Barack Obama on Dec. 27 ordered 35 Russian diplomats expelled from the United States and closed down two East Coast "vacation" estates used by Russian diplomats. During the same period, U.S. intelligence agencies routinely intercepted the communications of Sergey Kislyak, Russia's ambassador to the United States, and monitored troubling communications between Flynn and Kislyak. The upshot was that Russians were assured things would be different after Trump's inauguration.

When the story broke, Flynn denied that Obama's sanctions were discussed. He made the same assertion to Vice President-elect Mike Pence, who repeated the denial on national television. It now turns out that:

—While Flynn did not specifically promise that the Trump administration would lift the sanctions, he strongly hinted at it. In his resignation letter Monday, Flynn wrote, "Unfortunately, because of the fast pace of events, I inadvertently briefed the vice president-elect and others with incomplete information" about the phone call.

—After Trump's inauguration Jan. 20, Sally Q. Yates, the acting attorney general, warned Donald McGahn, Trump's White House counsel, that Flynn had misled administration officials about the nature of his communications with Kislyak, making him potentially vulnerable to Russian blackmail. The Washington Post reported that what McGahn did with that information is not known, but Yates was fired on Jan. 31 for refusing to enforce Trump's executive order on immigration.

The question that Republican Sen. Howard Baker of Tennessee asked during the 1973 Watergate hearings is pertinent today: "What did the president know and when did he know it?" The Trump White House asserts, unconvincingly, that it was "misled" by Flynn.

It could be that in the demolition derby that passes for Trump's West Wing operations, nobody recognized the danger Flynn's back-channel communications posed. Flynn has been sympathetic to the Putin government, as has Stephen K. Bannon, Trump's chief strategist. In 2008, Donald Trump Jr. said his father's business organization sees "a lot of money pouring in from Russia."

No one knows for sure. Congress must grow a spine and compel testimony under oath. Country comes before party.

REPRINTED FROM THE ST LOUIS POST DISPATCH