REUTERS

Viktor Pinchuk, a well-known Ukrainian oligarch, has links to Washington that stretch back to 2001 when he hired Kroll, an investigative agency, to whitewash President Leonid Kuchma's involvement in the murder of journalist Georgiy Gongadze, Kuzio wrote in his article for The Hill.

In 2003-2004, Pinchuk brought U.S. VIPs, such as Henry Kissinger, Zbigniew Brzezinski and President George H.W. Bush to Ukraine to improve Kuchma's international image. Pinchuk also hired Black, Kelly, Scruggs & Healey (BKSH) Associates and the Washington World Group for public relations work.

Pinchuk has also provided donations to both Democrats and Republicans, the author said.

Ukrainian gas tycoon Dmytro Firtash has a more colorful background and is wanted by the U.S. on corruption charges and by Spain for money laundering with Russian organized crime. Firtash hired Jack Abramoff, who had spent three years in jail after working with Israeli consultant Aron Shaviv, to thwart U.S. requests for his extradition and to promote his newly created Agency for the Modernization of Ukraine.

Read alsoManafort falsified invoice to Belize company to legitimize Yanukovych's $750,000 payment to himself – Ukrainian MPSix years earlier, Zev Furst, president of First International Resources, and Firtash had met U.S. Ambassador to Ukraine William Taylor where he admitted to being permitted to operate in the highly-opaque gas business by Russian mafia don Semyon Mogilevich, who has been on the FBI wanted list since the 1990s for multi-million-dollar fraud schemes.

Firtash and Mogilevych have always worked for Russian Presidents Borys Yeltsin and Vladimir Putin.

Kuzio also said that Yanukovych and his oligarchic allies had hired American consultants, lobbyists and lawyers to a greater degree than any other group of Ukrainians. From 2002-2004, his government had an established relationship with a range of U.S. consultancies.

Read alsoAP confirms Manafort firm received Party of Regions ledger payoutAfter the 2004 Orange Revolution, Davis Manafort International was recommended to Yanukovych's long-term ally, oligarch Rinat Akhmetov. Davis Manafort International worked in Ukraine and in the U.S. but never registered with FARA in 2005-2014. Manafort headed Trump's election campaign but resigned after extensive media coverage of his nefarious activities. Manafort's work for Yanukovych became public through the FARA registration of Daniel J. Edelman.

President Yanukovych also hired Democrats and Republicans. In addition, leading U.S. law firms have been hired by Ukrainian kleptocrats, the author stressed.