Behind the scenes: How Ukraine's military aid was held up

What emerges is the story of how Mr. Trump’s demands sent shock waves through the White House and the Pentagon, created deep rifts within the senior ranks of his administration, left key aides like Mr. Mulvaney under intensifying scrutiny — and ended only after Mr. Trump learned of a damning whistle-blower report and came under pressure from influential Republican lawmakers…

Opposition to the order from his top national security advisers was more intense than previously known. In late August, Defense Secretary Mark T. Esper joined Secretary of State Mike Pompeo and John R. Bolton, the national security adviser at the time, for a previously undisclosed Oval Office meeting with the president where they tried but failed to convince him that releasing the aid was in interests of the United States.

By late summer, top lawyers at the Office of Management and Budget who had spoken to lawyers at the White House and the Justice Department in the weeks beforehand, were developing an argument — not previously divulged publicly — that Mr. Trump’s role as commander in chief would simply allow him to override Congress on the issue.