This is the inquiry on the BBC World Service with me Ruth Alexander.

Each week one question, four expert witnesses and an answer. On the 25th of July 2019, the President of the United States made a phone call to the recently

elected President of Ukraine congratulating him

on his party's election victory. What Donald Trump said in that call to

Vladimir Zelensky has ended up threatening his own presidency.

I would like you to do as a favour, President Trump told the Ukrainian leader,

asking him to investigate one of his rivals for the 2020 US presidential election,

Democrat Joe Biden.

There's a lot of talk, President Trump said. It sounds horrible to me. This call has

triggered the impeachment of the president.

Donald Trump says his interest was in rooting out corruption. Meanwhile, Joe Biden's role in Ukraine was to do the same, root out corruption.

So we want to know why does Ukraine have such a corruption problem?

Parts a corruption problem. Part 1, a license to print money. There's a case Ukrainian saying, you know, poor Ukraine so near to Russia and so far from God.

Oliver Bulow, our first expert witness, is a journalist and author of Moneyland, a book about financial crime.

He's going to help us understand how Ukraine's wealth became concentrated in the hands of

a very few people.

There is no natural border between Ukraine and Russia,

so the Russian influence has been very strong for hundreds of years.

Ukraine was part of the Russian Empire from the 1700s.

After a very brief period of independence, it was subsumed into the Soviet Union in

1921, meaning it was a republic with its government and economy run according to Moscow's design.

It's not true to say Ukraine was totally suppressed by the Soviet Union.

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