Ukraine derives its name from a word that means “borderland.” And since the collapse of the USSR in 1991, Ukraine has been on the frontier of a clash between East and West. The map makes it fairly obvious: Ukraine is sandwiched between Russia and the European Union. Unlike former Communist countries like Poland or Hungary, Ukraine never joined NATO. Ukraine shares borders with the European Union, but it has not yet become a member. Trump's Ukraine scandal: Who's who?And as one of the poorest countries in Europe, Ukraine has been a major recipient of US assistance: Since 1992, the first full year of independence, the US Agency for International Development has contributed more than $3 billion in development assistance to Ukraine.Why would stabilizing a country on the edge of Europe be a priority for Washington? Nukes, for starters. The demise of the Soviet Union created a potential nightmare for policymakers: An independent state had just appeared on the map that, after inheriting part of the Soviet Union’s nuclear arsenal, had become home to the third largest nuclear arsenal in the world. Read MoreKremlin’s suspicionIn 1994, the United States, together with the United Kingdom, Russia and Ukraine, signed a memorandum providing Kiev with security assurances. In exchange for signing on, Ukraine would give up its nuclear weapons; the signatories pledged to uphold Ukraine’s territorial integrity.That guarantee was effectively chucked out the window by Russia. The Kremlin had watched with suspicion as NATO expanded eastward to include the Baltic states, which had been absorbed by force into the Soviet Union. For Russian President Vladimir Putin, Ukraine’s Western-leaning aspirations were impermissible: the US, in his paranoid worldview, was pulling the strings in Ukraine’s democratic revolution of 2014. Following the ouster of Ukraine’s pro-Russian president, Viktor Yanukovych, Moscow occupied and annexed the Crimean peninsula.Putin emerges as a winner in Washington's Ukraine turmoilThe US and its allies imposed wide-ranging sanctions on Russia over Crimea and for Moscow’s support for separatists in eastern Ukraine. The US also provided security assistance to Kiev, though the Obama administration stopped short of providing lethal aid to Ukraine.That policy drew vocal criticism from late Republican Sen. John McCain in 2015 for being inadequate. But during the 2016 presidential race, Republicans also seemed to waver when the Trump campaign amended language in the party platform that endorsed the US government sending lethal arms to Ukraine and bolstering Ukraine’s anti-corruption efforts.The report of special counsel Robert Mueller subsequently said its investigation “did not establish that one campaign official’s efforts to dilute a portion of the Republican Party platform … were undertaken at the behest of candidate Trump or Russia.” Russia’s President Vladimir Putin visits the Crimean port of Sevastopol in May 2014.The Manafort connectionWhat the Republican 2016 convention did do, however, was cast a spotlight on Trump campaign chairman Paul Manafort’s financial ties to Ukraine. Manafort had worked as a political consultant for Ukraine’s former pro-Russian ruling party and for Yanukovych, who fled the country after violent street demonstrations in 2014.Manafort is now behind bars after being sentenced earlier this year for tax fraud, hiding his foreign bank accounts and defrauding two banks for more than $4 million in loans.Paul Manafort arrives at Manhattan Supreme Court in June 27, 2019.The Manafort saga showed the amount of shady money that seemed to be sloshing around in Ukraine. In 2016, Ukrainian lawmaker Sergii Leshchenko made public the “black ledger, a once-secret list of payments made by the Party of Regions, Yanukovych’s party, to Manafort and others. The ledger has figured in the latest round of scandal: Over the past year, Rudy Giuliani, Trump’s personal lawyer and political attack dog, had begun spinning an elaborate counter-narrative over foreign interference in the 2016 election, saying it could all be traced back to Democrats’ dealings in Ukraine.Giuliani has circulated a claim that Leshchenko interfered in the 2016 US elections, a claim Leshchenko says was effectively knocked down in July by a Ukrainian administrative court ruling in the matter.But Giuliani also zeroed in on another Ukraine narrative: pushing for investigation of former US Vice President Joe Biden and his son Hunter, who had a lucrative job on the board of a Ukrainian natural gas company, Burisma.There is no evidence of wrongdoing by either Joe or Hunter Biden. But the optics were not great, particularly when one of Joe Biden’s jobs as vice president was to badger the Ukrainian government about shoring up the rule of law.Rudy Giuliani has spun an elaborate counter-narrative over foreign interference in the 2016 election, saying it could all be traced back to Democrats’ dealings in Ukraine.A previous president in the spotlightThe Trump administration did approve the provision of lethal arms to Ukraine, including Javelin anti-tank missiles, something long sought by Kiev. But the Trump administration’s hold on $400 million military assistance to Ukraine is now at the heart of the whistleblower complaint that has spurred calls for impeachment. Questions remain about the July 25 phone call between Trump and Ukrainian President Volodymyr Zelensky when Trump pressed him to investigate the Bidens — at a moment when a hold on aid was in place. This not the first time a US president has landed in hot water over Ukraine.US President Trump pressed his Ukrainian counterpart Volodymyr Zelensky to investigate former US Vice President Joe Biden (pictured center), and his son Hunter (left).On August 1, 1991, then-President George H.W. Bush gave a speech to the Verkhovna Rada, the parliament of Ukraine, then part of the Soviet Union. In his remarks, Bush warned against “suicidal nationalism:” At the time, republics of the USSR were clamoring for greater independence from Moscow, and the Bush administration was concerned about a potentially violent breakup of a nuclear-armed superpower.Such advice may have seemed prudent at the time. Ethnic conflict was already tearing Yugoslavia apart, and in the Soviet Union, open warfare was underway between Armenians and Azeris over the mountainous enclave of Nagorno-Karabakh. But Bush had profoundly misread the desire of Ukrainians for statehood. Within weeks, the Ukrainian parliament declared independence. Later that year, Ukrainians voted overwhelmingly in a referendum for withdrawal from the Soviet Union. William Safire, the influential New York Times columnist, called Bush’s remarks the “Chicken Kiev speech.”In retrospect, the quibble over Bush’s remarks in Kiev looks quaint compared to the political controversy that is now hitting Washington. That storm is now set to engulf Ukraine.