US Secretary of State Mike Pompeo has been subpoenaed.
A Democratic-led US House of Representatives committee issued the order on Friday.
They want to him to hand over documents regarding contact the US government had with the Ukrainian government.
Earlier this week House Speaker Nancy Pelosi launched a congressional impeachment inquiry of US President Donald Trump.

Trump says operation to reopen Strait of Hormuz will be 'paused'
Hantavirus-hit cruise ship to head to Spain after granted permission
Trump says Iran should wave the white flag of surrender
Pentagon chief says ceasefire with Iran is not over
US and Iran launch new attacks as they wrestle for control of Strait
