The demonstration was done in conjunction with the Kallio church, according to a Greenpeace press release.
President Trump will meet Putin on Monday in Helsinki, Finland.
The Finnish capital is no stranger to high-stakes Moscow-Washington summits.
Trump boasted that the NATO leadership is very fond of him, but says Russia must be thinking "if we did like this guy, we made a big mistake."
The president broke diplomatic norms in hopes of de-nuking North Korea. But the dealmaker-in-chief got little to nothing in Singapore.
Trump reportedly told French President Emmanuel Macron that "all the terrorists are in Paris."
Trump urged photographers to make him and the North Korean leader look "handsome and thin."
Donald Trump's summit with North Korean leader Kim Jong Un may last only a few hours—but that's enough time to worry leaders in Beijing and Tokyo.
President Donald Trump's top economic adviser launched a unusually critical campaign against Canadian Prime Minister Justin Trudeau Sunday morning, and placed the blame on Canada for Trump's refusal to sign the G-7 joint agreement.
The Russian leader spoke as Trump prepares to meet with Kim Jong Un.
Alongside Japanese Prime Minister Shinzo Abe, President Trump remarked on his upcoming summit with North Korean leader Kim Jong Un.
Asked if he would welcome Kim Jong Un to the U.S. after the Singapore summit, Trump said, "Yes."