KURT VOLKER, A former US ambassador to NATO caught in the middle of a whistleblower complaint over President Donald Trump’s dealings with Ukraine, has resigned from his post as special envoy to the Eastern European nation.

The move came as House Democrats took their first concrete steps in the impeachment investigation of Trump, issuing subpoenas demanding documents from Mike Pompeo and scheduling legal depositions for other State Department officials.

A US official, who spoke on condition of anonymity, said Volker told Secretary of State Pompeo on Friday of his decision to leave the job.

The move followed disclosures Volker had connected Trump’s personal lawyer Rudy Giuliani with Ukrainian officials to investigate former vice president Joe Biden and his family over allegedly corrupt business dealings.

The State Department had no immediate comment on Volker’s resignation and has said only that he put Mr Giuliani in touch with an aide to Ukraine’s President Volodymyr Zelenskiy.

Volker’s departure comes hours after Democrats subpoenaed Pompeo for Ukraine-related documents.

The heads of three House committees gave Pompeo one week to produce the documents, saying a number of State Department officials have direct knowledge of Trump’s efforts to enlist the Ukraine government’s help in his domestic political campaign for reelection.

“The Committees are investigating the extent to which President Trump jeopardized national security by pressing Ukraine to interfere with our 2020 election and by withholding security assistance provided by Congress to help Ukraine counter Russian aggression,” they said.

“The subpoenaed documents shall be part of the impeachment inquiry and shared among the Committees. Your failure or refusal to comply with the subpoena shall constitute evidence of obstruction of the House’s impeachment inquiry,” they wrote.

The subpoena came one day after the release of an intelligence official’s bombshell whistleblower complaint that describes Trump pressuring Ukraine’s President Volodymyr Zelensky in a 25 July phone call to supply dirt on Democratic political rival Joe Biden.

With reporting from © AFP 2019