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.

Netanyahu says Israel will remain in Gaza until Hamas disarms
Ukraine, Russia accuse each other of lethal attacks
Air India pilot undergoes further testing after initial screening result
Thailand school shooting toll rises to nine after death of 12-year-old girl
Typhoon Dolphin hits China's east coast, over 1 million evacuated
