As the US pushes forward with impeachment hearings into President Donald Trump and his dealings with Volodymyr Zelensky, the Ukrainian leader is set to sit down Monday with the man overseeing another conflict involving his country: Russian President Vladimir Putin.

Joe Biden this week had a tense exchange with an audience member during an Iowa town hall who had asserted, among other things, that the former vice president is "too old" to helm the White House.

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The organizers of the large-scale demonstrations which kicked off Hong Kong's months-long protest movement earlier this year are taking to the streets again Sunday, in a bid to maintain pressure on the city's government following the success of pro-democracy groups at recent elections.

SpaceX's Dragon capsule successfully docked with the International Space Station early Sunday morning, NASA said.