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.
US hits five Iranian oil tankers after attack on Navy ships
The United States has destroyed five Iranian oil carriers on Tuesday after the Islamic Revolutionary Guard Corps (IRGC) targeted its navy warship with ballistic missiles "twice over the past two days".
Jordan intercepts 18 Iranian ballistic missiles
Jordanian army forces have intercepted 18 Iranian missiles targeting the country early on Wednesday.
Air traffic control issue disrupts flights at major UK airports
Flights at major British airports were disrupted on Tuesday by a technical fault at air traffic control provider NATS, the latest in a series of failures that renewed questions about the resilience of Britain's aviation infrastructure.
At least 73 injured after Houthi rebels attack Saudi civilian and energy facilities
At least 73 civilians have been injured after Yemen's Houthi rebels attacked a number of civilian and energy facilities in Saudi Arabia's southern region on Tuesday, state media confirmed.
UK, France and Canada sanction Israeli West Bank settlements
Britain, France and Canada on Tuesday moved to block imports from Israeli settlements in the occupied West Bank, as a wider group of countries signalled further steps to defend the two-state solution amid mounting concern over settlement expansion.
