Biden, Ukraine leader Zelensky meet, in countries' up-and-down relationship since Obama

President Biden will meet Wednesday with Ukraine President Volodymyr Zelensky, who emerged as a central figure during an impeachment trial for former President Trump and in the 2020 presidential elections. 

"This visit will affirm the United States’ unwavering support for Ukraine’s sovereignty and territorial integrity in the face of Russia’s ongoing aggression," the White House has said.

However, the relationship between the United States and the small Eastern European country has in fact been shaky since Biden was vice president under President Obama.

In 2014, Russia annexed Ukraine's Crimea peninsula and backed separatists in a conflict in Ukraine's eastern Donbass region, which Ukraine says has killed 14,000 people, according to Reuters. 

Obama imposed economic sanctions, but his actions fell short for Republicans including then-Arizona Sen. John McCain who wanted the U.S. to send arms. 

Trump as president in 2017 asked aloud on Twitter: “Crimea was TAKEN by Russia during the Obama Administration. Was Obama too soft on Russia?”

A year later, amid reports that President Obama-appointed U.S. Ambassador to Ukraine Marie Yovanovitch was badmouthing him, Trump reportedly said: "Get rid of her! "Get her out tomorrow. I don't care. Get her out tomorrow. Take her out. OK? Do it."

Biden and Zelensky will also reportedly discuss the White House's backing of Zelensky's efforts to tackle corruption and implement a reform agenda based on “shared democratic values," Reuters also reports.

The United States’ relationship with Ukraine has also been marked by Zelensky’s unwilling involvement in events leading to the first of Trump’s two impeachment trials.

Trump was impeached by the Democrat-controlled House in 2019 over what White House aides described as an effort to withhold nearly $400 million in aid and a coveted White House visit unless Ukrainian officials announced investigations into Biden, then a Democratic presidential candidate, and his businessman son, Hunter Biden, the wire service also reports.

The GOP-controlled Senate did not convict Trump on the charge. 

The leaders are also set to discuss energy security, after the Biden administration announced a deal last month with Germany intended partly to allay Ukrainian concerns about the Nord Stream 2 pipeline being built under the Baltic Sea to carry gas from Russia's Arctic region to Germany, according to Reuters.

Kyiv fears Nord Stream 2 will be used as a geopolitical weapon by Russia and has sought guarantees over its status as a gas transit country once the pipeline becomes operational.