When a British national inspired by Islamic State plowed through crowds on London's Westminster Bridge on March 22, killing four and injuring many others, acts of solidarity with the UK took place around Europe.
That night, the Eiffel Tower went dark in Paris, an all-too familiar act of national mourning in France in the wake of the last few years of terror attacks there. In Germany, the UK's Union Flag was projected onto Berlin's Bradenburg Gate in another public demonstration of solidarity from one state to another.
Yet as Russia mourns the victims of a terrorist attack that killed 14 and injured 39 at a St. Petersburg metro station on Monday, the response from many European neighbors have been notably lackluster. The absence of prominent memorials has prompted many -- mostly Russians -- to rally around the victims on social media using the hashtag #PrayforStPetersburg.
The mayor of Paris, Anne Hidalgo, has turned off the Eiffel Tower's lights a handful of times in the past -- not just in response to domestic or European terror attacks, but also as an act of solidarity for the residents of war-ravaged Aleppo. On Tuesday afternoon, Hidalgo's office confirmed to CNN that they would again extinguish the lights of their world-famous landmark at midnight for the victims of the St. Petersburg attacks.
But many still rue the international response. Blogger Cristiano Alves tweeted, "It's curious how differently from Paris terror, Facebook did not create any filter with Russian colours," referencing the social media giant's response to the Parisian terror attacks, which allowed users to temporarily add the French flag to their profile picture.
In Russia, a three-day mourning period for the victims began on Tuesday, with President Vladimir Putin placing flowers at a memorial at the St. Petersburg Technological Institute metro station.
France was not alone in criticism from Russian commentators. Germany has yet to indicate if the Bradenburg gate will adorn the Russian flag in solidarity with those who have died. Last June, the Berlin landmark blasted a rainbow flag onto its gate, honoring the LGBT victims of the Orlando nightclub shooting. In January, the Israeli flag was projected onto the gate after a driver plowed a truck into a group of soldiers in Jerusalem, killing four and injuring at least 10.
A Berlin Senate spokesperson told German broadcaster RBB that the Bradenburg gate would only alight with special colors for terrorist victims in exceptional cases or in "partner cities." Considering Berlin appears to have made exceptions to this rule in the past, it has prompted questions about why the St. Petersburg metro blast has so far gone unacknowledged. CNN has asked the Berlin authorities for comment.
Berlin-based writer Jon Worth tweeted, "An argument like this was inevitable. (UK flag) on Brandenburg Gate for London attack, but nothing for St Petersburg."
Israel is one of the few nations to honor the St. Petersburg attack victims publicly so far. On Monday night, the Tel Aviv City Hall was emblazoned with Russian tricolors. The city's mayor, Ron Huidal, wrote on Twitter, "In solidarity with our friends in #SaintPetersburg, #TelAviv city hall is lit tonight in the colors of the #Russian flag."
Despite the lack of adorned landmarks, an outpouring of support has been seen online with European leaders paying their tributes directly to Putin. The Kremlin earlier announced that French President Francois Hollande and German Chancellor Angela Merkel expressed their condolences.
European Council President Donald Tusk wrote on Twitter to pay homage to the victims: "My thoughts are with the victims of the #StPetersburg metro explosion and their families and loved ones."