WASHINGTON               -        President Donald Trump launched a Twitter attack on a former US ambassador to Ukraine on Friday while she was testifying to an impeachment hearing in Congress, in an extraordinary moment that Democrats said amounted to witness intimidation. Trump blasted Marie Yovanovitch, a career diplomat, as she explained to the second day of televised impeachment hearings how she had fought corruption in Ukraine and how the Trump administration abruptly removed from her post earlier this year. Democrats say Yovanovitch was pulled back to Washington to clear the way for Trump allies to persuade Ukraine to launch corruption probes into Democratic presidential contender Joe Biden and his son Hunter, who was on the board of a Ukrainian energy company. Trump’s pressure on Ukraine is at the heart of the Democratic-led impeachment inquiry into whether the Republican president misused US foreign policy to undermine one of his potential opponents in the 2020 election. As Yovanovitch testified, Trump fired off criticism on Twitter in a move Democrats labelled “real-time” witness intimidation.  “Everywhere Marie Yovanovitch went turned bad. She started off in Somalia, how did that go?” Trump asked.  In the most dramatic moment of the public impeachment hearings that began on Wednesday, Representative Adam Schiff, who is chairing the hearing in the House Intelligence Committee, asked Yovanovitch for her reaction to the tweet. She said it was “very intimidating.” “I can’t speak to what the president is trying to do, but I think the effect is to be intimidating,” she said. Schiff replied: “Well, I want to let you know, ambassador, that some of us here take witness intimidation very, very seriously.” Afterward, Democratic Representative Eric Swalwell, a member of the committee, told reporters the Trump attack could be considered for a separate article of impeachment against Trump for obstruction of justice. “It’s evidence of more obstruction: intimidating, tampering with the witness’s testimony,” he said.