In the US, the dispute over a possible impeachment trial against President Donald Trump escalates. The White House now officially rejects any cooperation with the ongoing preliminary investigation. In other words, there are no documents or statements from government employees. The New York Times spoke of a declaration of war. It could play into the hands of the president's opponents.

1. How does the White House justify the blockade? - The Legal Department's letter to leading Democrats in Congress said the preliminary investigation was an illegitimate attempt to "overturn the outcome of the 2016 presidential election." In order to fulfill its obligations, the President could not take part in a "party-political and unconstitutional" preliminary investigation.

Previously, the White House had forbidden US Ambassador to the European Union, Gordon Sondland, to testify before Congress at the last moment. Sondland is considered the central figure in the Ukraine affair that triggered the preliminary investigation. Forcing the co-operation of the administration in court should drag on for months.

2. How do the Democrats react to the blockade? - The Democrats accuse the White House of obstructing constitutional control by Congress. They now see themselves in a win-win situation: Either the White House is removing incriminating material or they expand the allegations against Trump for disability. But there is a historical template: Even Richard Nixon was accused in 1974, the Congress to have withheld information. Nixon came before a impeachment by resignation.

3. What new findings are there in the Ukraine affair? - Trump has urged the Ukrainian president to initiate corruption investigations against his democratic rival Joe Biden. The minutes of the telephone call do not speak directly about an offsetting transaction. But it has since become clear that both in Trump's environment and in Kiev it must have been clear that ammunition for Trump's election campaign was the prerequisite for the payment of frozen aid to Ukraine and for the invitation of the new Ukrainian president to the White House. This is u. a. from text messages exchanged with US diplomats dealing with Ukraine, including Sondland. Which explains why the White House does not want insiders to testify before Congress.