The Ukrainian officials arrived at the White House on July 10 hoping to cement their country’s relationship with the United States, solidifying support the Trump administration seemed reluctant to extend for reasons they didn’t fully understand.

Instead, they walked into a White House that was on the verge of a crisis over Ukraine, as a simmering conflict between the president’s political impulses and the nation’s security priorities was about to erupt in the West Wing.

In a pair of volatile meetings, senior White House officials, including then-national security adviser John Bolton, were confronted with the outlines of a scheme they had previously only suspected: President Trump was seeking to use the power of his office to pressure Ukraine to deliver damaging information on former vice president Joe Biden and his son.

One of the officials Trump had entrusted to pursue this agenda, Ambassador to the European Union Gordon Sondland, was undeterred by the fierce opposition from Bolton and others. He persisted in pressing Ukraine to commit to Trump’s demands, convening a second meeting even after a spectacular blowup in the West Wing.