The whistleblower complaint that has triggered a standoff between Congress and the U.S. intelligence community involves President Trump and Ukraine, The Washington Post reports. The complaint—reportedly filed on Aug. 12 by an intelligence official who had worked at the White House—pointed to communications between Trump and a foreign leader involving an unspecified “promise.” The complaint was filed to the intelligence community's inspector general, who deemed it alarming enough to notify Congressional oversight committees. Lawmakers have since demanded the complaint be handed over, but the acting Director of National Intelligence has reportedly not done so after seeking legal guidance with Justice Department officials.

About two and a half weeks before the complaint was filed, Trump spoke with Ukrainian President Volodymyr Zelensky, who was elected into office in May. Trump's call with Zelensky has attracted scrutiny by House Democrats who are probing whether Trump's personal attorney, Rudy Giuliani, sought to manipulate Ukraine's government into helping Trump's re-election efforts with investigations that would be beneficial to Trump. According to a Ukrainian readout of the July 25 call, Trump told Zelensky he hoped the new government would complete corruption investigations that had “hampered cooperation between Ukraine and the USA.” Military aid was also recently reinstated to Ukraine.

The White House has not commented on the matter, but Trump denied doing anything improper earlier Thursday. “Virtually anytime I speak on the phone to a foreign leader, I understand that there may be many people listening from various U.S. agencies, not to mention those from the other country itself,” he wrote in a Thursday tweet. Giuliani brushed off concerns of the complaint and an alleged “promise” to a foreign leader. “If I’m not worried about it, he’s not worried about it,” he told the Post.