Donald Trump inside the under-construction Trump International Hotel in Washington in March 2016. In 2014, Deutsche Bank agreed to lend the Trump Organisation up to $US170 million to finance the gut renovation of the hotel. Credit:ZACH GIBSON One had to be a little awed by Trump's nose-thumbing response. Instead of paying up, he counter-sued. He argued that Deutsche Bank had co-created the financial downturn. Or as he put it: "Deutsche Bank is one of the banks primarily responsible for the economic dysfunction we are currently facing." Therefore, he was not obliged to pay back any money. Therefore, Deutsche Bank owed him money. He wanted $US3 billion in damages.

Donald Trump at the Taj Mahal casino in Atlantic City in 1996, one of a string of bankruptcies in the 1990s that alienated him from major US lenders. Credit:CHESTER HIGGINS JR The same day he argued that the depression meant he was off the hook, Trump gave an interview to The Scotsman newspaper. After a two-year fight, he had succeeded in getting approval from the Scottish government for a new Trump golf resort near Balmedie in Aberdeenshire. "The world has changed financially and the banks are all in such trouble, but the good news is that we are doing very well as a company and we are in a very, very strong cash position," Trump told the newspaper. Anshu Jain, right, and Juergen Fitschen, then co-chief executives of Deutsche Bank, during a news conference in Frankfurt in 2013. Credit:RALPH ORLOWSKI Trump's outrageous behaviour vis-a-vis Deutsche Bank might have been anticipated. He was, after all, someone who had been through a slew of corporate bankruptcies. His Taj Mahal casino, his other casinos in Atlantic City, his Plaza Hotel in NYC all filed for chapter 11 bankruptcy in the early 1990s.

After those failures, US banks that had previously advanced the capital to Trump for building projects, believing them to be sound investments, stopped lending. Chase Manhattan, Citibank, and other burned Wall Street houses declined further credit and refused his calls. The Trump National Doral resort in Florida, which Deutsche Bank's private wealth wing allowed Trump to mortgage twice. Credit:ILANA PANICH LINSMAN The one institution willing to advance him loans in the new century was Deutsche Bank. In 2010 Trump settled his feud with Deutsche. This was done, extraordinarily, by borrowing more money from … Deutsche Bank. The Trump International Hotel in Washington, which Deutsche Bank's private wealth wing helped pay for. Credit:AL DRAGO

Shut out from its real estate division, Trump turned to another part of the same institution - Deutsche's private wealth division, which typically deals with high net worth individuals. It doesn't normally do property. Still, the unit lent him the money. And later gave him another $US25 to $US50 million in credit. Asked whether it was normal to give more money to a customer who was a bad credit risk and a litigant, one former senior Deutsche staff member said: "Are you f---ing kidding me?" Robert Mueller, the Justice Department's special counsel, in Washington in June. Credit:DOUG MILLS Remarkably, Trump was able to borrow even bigger sums. He took out two mortgages against his Trump National Doral resort in Miami. And a $US170 million loan to finish his hotel in Washington in the old post office tower. These loans flowed from the private wealth wing. According to an analysis by Bloomberg, by the time he became the 45th president, Trump owed Deutsche Bank around $US300 million. All four debts were due in 2023 and 2024. This was an unprecedented sum for an incoming president and one that raised awkward questions about conflict of interest. If Deutsche Bank were to get into regulatory difficulty, one of the bodies that would investigate was the Department of Justice. Which reported to Trump. It was hard to see how the department could work dispassionately. Or how Deutsche might take legal action against a sitting president if he defaulted again.

Collusion by Luke Harding. Credit:NEW YORK TIMES From Russia to New York: the Deutsche connection During the same period Deutsche was doing something abnormal - something that would provoke the interest of regulators, and in turn lead to punishment. The bank was laundering money. Russian money. Not small amounts but many billions of dollars. This dubious tide flowed from Moscow to London, and from London to New York. In 2005 Deutsche bought UFG, a boutique investment bank already well established in Moscow. The man behind Deutsche's aggressive expansion was Anshu Jain, its future co-chief executive. Jain came up with a controversial strategy: to tap into potentially huge Russian profits, he decided to forge relationships with state partners. Former head of MI6 Richard Dearlove in 2008. Credit:AP

Russia's most powerful banker was Andrey Kostin. Kostin had served in Sydney and London as a Soviet diplomat. Intelligence sources think he was a KGB spy. In the 1990s, he became head of Vnesheconombank - VEB - a state development bank described by one former CIA analyst as the "Kremlin's cookie jar". Then Putin made Kostin head of Vneshtorgbank, or VTB, also state-run. Jain and Deutsche Bank recruited Kostin's twenty-something son, also called Andrei, with an i. In spring 2007 Kostin jnr moved from a posting in London to Deutsche Bank in Moscow. Suddenly, he got massive flows of business. According to one estimate, Deutsche Bank's Moscow subsidiary began notching up profits of $US500 million to $US1 billion a year, with VTB generating somewhere between 50 and 80 per cent of all revenue. In Moscow, a Russian client bought blue-chip Russian stocks from Deutsche Bank Moscow in companies like Gazprom or Sberbank. The payment was in roubles. The size of a typical order was $US2 million to $US3 million. Shortly afterwards a non-Russian "customer" sold exactly the same number of securities to Deutsche Bank in London, paying in dollars. These "mirror trades" were fake and had no economic logic. The selling parties were based in offshore territories like Cyprus or the British Virgin Islands. Billions were moved out of one Deutsche Bank, from its modern glass office at Building 2, 82 Sadovnicheskaya Street, to another Deutsche Bank, at 60 Wall Street. There were nearly 6000 transactions. Nobody in New York or London or Frankfurt or any of the international financial centres really noticed.

The end came in August 2015, when Deutsche Bank suspended American Tim Wiswell and then fired him. After that, he disappeared. There were Facebook postings from South-east Asia and Bali, where the Wiswells went with their two small children. He appeared to be on the run from US authorities and is now allegedly back in Moscow. One friend described him to The New Yorker as "finance's Edward Snowden". In a wrongful dismissal suit Wiswell said he'd been scapegoated. Around 20 colleagues, including two senior managers in London, knew all about the trades, he said. The affair was a grievous blow to Deutsche Bank's reputation. The New York State Department of Financial Services (DFS) - which has the power to suspend any bank with a branch in New York - fined Deutsche $US475 million. London's Financial Conduct Authority imposed a £163 million ($282.2 million) penalty. The bank carried out an internal review, Project Square. The review did not identify the Russians behind the scheme. We don't know who they were or where the billions went. Or where the money came from in the first place. A Kremlin bank, VTB, had seemingly captured Deutsche Bank's Moscow outpost. Deutsche's London and New York divisions were economic beneficiaries of this arrangement. While this was going on, Deutsche Bank in New York lent hundreds of millions of dollars to the future president. What Democratic senators and representatives wanted to know was this: Was there a connection? It was a good question.

Family ties My attempts to get information from Deutsche Bank over its lending to Trump were unsuccessful. House and Senate Democrats fared no better. There were legitimate things to ask. Such as: Had Deutsche sold any part of Trump's debt to foreign entities?

What meetings had the bank held with the Trump administration?

Had Trump or his family received preferential treatment?

Who decided to carry on lending to Trump after he defaulted in 2008?

Had Russia or Russian entities underwritten any aspect of these loans?

Was Deutsche shielding the President because of the Justice Department's ongoing investigation into mirror trades? Every inquiry, question, and query came up against a wall.

Overall, Germany's largest bank was in trouble. In 2005 the DFS reprimanded the bank for rigging the LIBOR, the main interbank lending rate. There was a further fine for sanctions busting - processing dollar transactions on behalf of entities in Iran, Libya, Syria, Myanmar and Sudan. And another $7.2 billion for selling high-risk mortgage-backed securities before the 2008 slump. Did Trump accept Russian sources of funding during these times? Richard Dearlove, the former head of MI6, said this question hangs over the President. Dearlove told the magazine Prospect: "What lingers for Trump may be what deals - on what terms - he did after the financial crisis of 2008 to borrow Russian money when others in the West would not lend to him." It wasn't just Donald Trump who maintained a warm relationship with Deutsche. The German bank looked after his entire family. Jared Kushner, Ivanka, and Kushner's mother Seryl Stadtmauer were all Deutsche clients. The Puck Building in New York, which securities filings show is involved in loans the Kushner Companies received from Deutsche Bank. Credit:New York Times According to our sources inside Deutsche, Trump's bid to become president made him a politically exposed person, or PEP. Deutsche reviewed its lending to Trump and his relatives, and the review was sensitive. Its goal was to discover if there was a Russian connection to Trump's loans. The DFS also requested information.

The sources insist that the answer was negative. No trail to Moscow was ever discovered, they told us. Deutsche, however, refused to make public comment. Nor would it provide details of its private review to Capitol Hill. Senators wrote letters; the bank stonewalled, citing privacy rules. Congress showed interest in mirror trades. It got the same evasive nein. In a letter to Bill Woodley, Deutsche's US chief executive, senator Chris Van Hollen expressed concerns about the bank's lending to Kushner. Kushner had a $US25 million line of credit with Deutsche. Additionally, in October 2016, it loaned him $US285 million. The loan was made around the time when Kremlin representatives were eagerly seeking Kushner's ear. Kushner first met Sergey Kislyak in April, when Trump gave his foreign policy speech at DC's Mayflower Hotel - just a handshake and pleasantries, Kushner said. Next came the meeting with Natalia Veselnitskaya. Then, on November 16, Kislyak got in touch again. By this point it was clear that Kushner would become senior adviser to the president. Kremlin-linked lawyer Natalia Veselnitskaya met with Donald Trump jnr and Jared Kushner. Credit:AP The Kushner-Kislyak meeting on December 1 took place at Trump Tower. Michael Flynn was present, too. Kushner made an unusual proposal. He asked Kislyak if it would be possible to set up a secret and secure communications channel between the Trump transition team and the Kremlin. The purpose, seemingly, was to keep any conversations hidden from the outgoing Obama administration and US intelligence.

Could this be done, Kushner wondered, by using Russian diplomatic facilities in the United States? The inquiry was staggeringly naive. If Kushner or Flynn were to drop by the Russian embassy, then US intelligence would certainly notice. The FBI didn't bug the conversation but learned of it afterwards, when Kislyak reported to his superiors back in Moscow. According to FBI intercepts of Russian communications, Kislyak was taken aback by Kushner's unusual request. Russia, it seemed, didn't need to expend much effort to get close to Trump's aides. Kislyak came up with a suggestion of his own. Perhaps Kushner would like to meet with another person from Moscow, someone with "a direct relationship" to President Putin? Jared Kushner: courted by Russian officials as a fixed point in the otherwise volatile Trump team. Credit:New York Times The details were agreed during a meeting on December 12 between Kislyak and Kushner's assistant, Avi Berkowitz. Putin's emissary turned out to be a banker, or more accurately, a banker-spy. His name was Sergei Gorkov. He was the head of VEB, the state development bank, which Kostin had run and whose board Putin had chaired during his four years as prime minister.

Gorkov had trained in the 1990s at the academy of the FSB [the successor to the KGB in handling state security], before joining the state-run Sberbank. Like VTB, Sberbank performed certain Kremlin functions. It was the official sponsor of the 2013 Miss Universe contest in Moscow, attended by Trump and hosted by Aras Agalarov. Eight days after the contest Sberbank announced it was lending Agalarov 55 billion roubles ($1.25 billion) to finance new projects. One of those under consideration was Trump's Moscow tower. Russian businessman Aras Agalarov, left, with Miss Universe Gabriela Isler and Donald Trump in Moscow in November 2013. Credit:Kommersant via AP VEB provided capital to build facilities at the Sochi Olympics and cash to secessionist rebels in eastern Ukraine. These top-down ventures lost money. VEB had large debts. The United States had included VEB, VTB and Sberbank in its 2014 sanctions package - the same package that led Putin to ban US couples from adopting Russian children. Gorkov's job was to restore the bank's fortunes. Gorkov was well prepared for his meeting with Kushner. He flew in from Moscow. On his plane were gifts. These were a piece of art and some earth carefully dug up and transported from the town of Novogrudok in north-west Belarus.The town was where Kushner's paternal grandmother, Rae Kushner, grew up. This subtlety was wasted. In evidence, Kushner said Putin's messenger had given him a "bag of dirt". It came from "Nvgorod," he wrote, spelling his grandmother's birthplace incorrectly.

Kushner characterised the encounter as brief, meaningless. Next Gorkov flew directly from New York to Japan, where Putin was attending a summit. The banker would have certainly reported to his boss. Aras Agalarov, right, with Russian President Vladimir Putin and Kremlin chief manager Vladimir Kozhin in Vladivostok in 2012. Credit:AP Targeting Kushner was logical. He was soon to become a federal employee. His portfolio included tax, banking policy, the military and international affairs. In a protean White House - where anyone could be fired - Kushner's status as the President's son-in-law made him unsackable. Loading During his meetings with Russians, Kushner said nothing about Moscow's attack on US democracy.

This is an edited extract from Collusion by Luke Harding (Faber), available now.

