Democrats in the US have subpoenaed the White House for documents they want to see as part of their impeachment investigation of President Donald Trump.
The chairmen of three House of Representatives committees said they wanted documents related to the phone call between Mr Trump and Ukrainian President Volodymyr Zelenskiy that is at the heart of their inquiry.
They said they were forced to issue the subpoena after the White House failed to produce documents they requested in September.
Representatives Elijah Cummings of the Oversight Committee, Adam Schiff of the Intelligence Committee and Eliot Engel of the Foreign Affairs Committee said: "We deeply regret that President Trump has put us - and the nation - in this position, but his actions have left us with no choice but to issue this subpoena."
They gave the White House until October 18 to produce the information, including who else besides the president was on the phone call with President Zelenskiy.
White House spokeswoman Stephanie Grisham said in a statement "This subpoena changes nothing - just more document requests, wasted time, and taxpayer dollars that will ultimately show the President did nothing wrong."
It comes after text messages revealed US diplomats encouraged Mr Zelenskiy to investigate Joe Biden's family in return for a visit to Washington.
One of them also called it "crazy" to withhold military aid "for help with a political campaign".
The messages were released by the House Intelligence Committee after Thursday's 10-hour interview with one of those involved, Kurt Volker.
The Biden family have not been shown to have committed any wrongdoing.
Mr Trump and the Ukrainian president have both denied that any untoward pressure was exerted.
Mr Trump has denied acting improperly in his dealings with Ukraine's president, calling the July phone call "perfect".
He has said the Democrats have started the impeachment investigation because "they know they can't win" in next year's election.
Mr Trump also suggested this week that China should "start an investigation into the Bidens".
Additional reporting by IRN