(Reuters) - The U.S. House of Representatives made headlines by formally launching an impeachment investigation into President Donald Trump, but there is debate among experts about the significance of the announcement.

U.S. President Donald Trump addresses a news conference on the sidelines of the 74th session of the United Nations General Assembly (UNGA) in New York City, New York, U.S., September 25, 2019. REUTERS/Jonathan Ernst

The following explains the nature of the investigation and how the televised announcement made by House Speaker Nancy Pelosi may move the process forward.

What led to Tuesday’s announcement?

The House move followed Trump’s admission on Tuesday that he encouraged Ukrainian President Volodymyr Zelenskiy to investigate former Vice President Joe Biden, the Democratic frontrunner in the 2020 presidential election.

“The actions of the Trump presidency revealed the dishonorable fact of the president’s betrayal of his oath of office, betrayal of our national security and betrayal of integrity of our elections,” Pelosi said. “Therefore, today, I’m announcing the House of Representatives is moving forward with an official impeachment inquiry.”

Trump says that call was perfectly acceptable, and that he did not pressure the Ukrainian president.

Weren’t Democrats already conducting a kind of impeachment investigation?

Yes. The House Judiciary Committee has been investigating whether to bring charges, known as articles of impeachment, against Trump. The House’s Democratic leadership has been cagey about whether that amounted to an actual impeachment investigation, however.

Judiciary Committee Chairman Jerold Nadler said in a Sept. 13 appearance on CNN that the probe could be described as an impeachment investigation but added that was a “made-up term” and that he was “not interested in the nomenclature.” Other party leaders have said an impeachment investigation was not underway.

Five other committees have been conducting their own investigations relating to Trump, including probes into his finances and his campaign’s contacts with Russia.

The investigations, which Trump has called “presidential harassment,” have moved slowly due to court battles over access to witnesses and documents.

So how does Pelosi’s announcement change things?

Pelosi put a new label on the various investigations and, perhaps more importantly, erased any doubt that Democrats were pursuing impeachment.

“I’m directing our six committees to proceed with their investigations under that umbrella of impeachment inquiry,” she said in her address.

The announcement moves the House closer to drafting articles of impeachment against Trump, according to Frank Bowman, a law professor at the University of Missouri who has written a book about impeachment.

Pelosi has long opposed impeachment as a politically risky move unless investigators find powerful evidence of misconduct that can unify public opinion. Tuesday’s address seemed to put her seal of approval on the process.

“As majority leader, she has the de facto if not the legal power to keep the Judiciary Committee or any other committee from driving full bore toward impeachment,” said Bowman. “That is the reality of the hierarchy of the House.”

Other impeachment experts said little has changed, however.

The announcement “was basically a press event with little or no practical or legal significance,” said Ross Garber, a lawyer in Washington who specializes in impeachment proceedings.

“The House has not passed a resolution,” Garber said. “No new powers were conferred on any committee. No new resources were allocated.”

What else might the announcement mean?

Past court decisions make clear that Congress has a stronger claim to documents and testimony when it is conducting an impeachment investigation, rather than asserting its traditional oversight powers, Bowman said. That means Pelosi’s announcement could help the House win its pending court battles with Trump.

Trump’s lawyers argue in those lawsuits that the congressional investigations are just partisan attempts to make him look bad, so he does not need to produce witnesses and documents.

The Trump administration is also asserting that some information sought by Congress is protected by “executive privilege,” a legal doctrine that allows the president to keep secret the nature of communications with advisers.