Reports of Russian military moving across the border into Ukraine caused a Twitter avalanche. Image from Twitter.

On Wednesday Russia expanded its push across the Ukrainian border, apparently sending troops and armor into the town of Novoazovsk in Donetsk region, in what the media described as a stealth invasion. Ukrainian social media users replied with thousands of posts, calling the world's attention to the alarming news.

As the first reports of Russian troops taking over new frontiers along the border appeared, Twitter and other social networks started sounding the alarm as users tried to decide how to raise awareness of the incursion. The situation clearly called for a hashtag, and one enterprising Belarusian user @belamova came up with just the thing:

Нужна 1000 ретвитов, чтобы вывести хештег о вторжении Рашки в мировые тренды #RussiainvadedUkraine

— РБ головного мозга (@belamova) August 27, 2014

We need 1000 retweets to get the hashtag about Russia's invasion into the world trends #RussiainvadedUkraine

The hashtag #RussiainvadedUkraine and its companion phrases spread like wildfire, with users providing directions for making them go viral to reach both Russian-speaking and Western audiences:

Пишем твиты на иностранных языках с хэштэгами #UkraineUnderAttack #RussiainvadedUkraine MAX RT

— Хуёвый Кривой Рог (@krivorozhanin_) August 27, 2014

Let's write tweets in foreign languages with hashtags #UkraineUnderAttack #RussiainvadedUkraine. MAX RT

The call to action was clearly taken up by Ukrainians on Twitter—in the first hour after the hashtag #RussiainvadedUkraine was born, it racked up over 100 thousand tweets and retweets, topping 350 thousand tweets later in the day. On Russian social network VKontakte, 3-5 posts tagged with the same hashtag popped up every second at the height of the flashmob. Netizens posted in Russian, Ukrainian, English and other languages, addressed various officials and international organizations, and of course, shared evocative art in order to draw attention.

HELP UKRAINE NOW #UkraineUnderAttack #RussiainvadedUkraine pic.twitter.com/47ypFLklrF

— Поміркований бандера (@mr_untitle) August 27, 2014

#russiainvadesukraine pic.twitter.com/Hr6pqKZ95h

— Civic Sector (@maidan_go) August 27, 2014

Along with regular users, official accounts also joined the hashtag flashmob, including the Ukrainian Ministry of Foreign Affairs:

#UkraineUnderAttack #RussiaInvadedUkraine RT PLZ pic.twitter.com/KMM9ezqAfv

— MFA of Ukraine (@MFA_Ukraine) August 27, 2014

Since the Ministry's tweet only contained the hashtags, some users, like KyivPost journalist Christopher Miller, wondered at how to interpret the message.

Is this the #Ukraine government's official announcement of a #Russia invasion, with hashtags? https://t.co/rH0JQkjkfU

— Christopher Miller (@ChristopherJM) August 27, 2014

With news of the invasion spreading, the hashtag #RussiainvadedUkraine was soon trending in Ukraine, and then went to the top of world Twitter trends, as seen in this screenshot posted to Twitter.

#UkraineUnderAttack #RussiainvadedUkraine #UkraineUnderAttack #RussiainvadedUkraine #UkraineUnderAttack pic.twitter.com/KGad3iPjq0

— Дно где-то рядом (@stabilizec) August 27, 2014

Although most of the tweets protesting Russia's border breach came from Ukrainians, some Russian social media users also joined the wave of outrage. A tweet by user Dmitry Monakhov, in which he announced he was going to protest Kremlin's actions on Manezhnaya square in Moscow, collected over 1700 retweets.

Я россиянин. Не быдло. Не убийца. И не оккупант. Мне стыдно что Путин мой президент. В 9.00 я иду на манежку против войны.

— Dmitry Monakhov (@dmtrmon) August 27, 2014

I am Russian. I am not a thug. I am not a killer. And not an occupant. I am ashamed to have Putin as my president. At 9:00 I am going to Manezhnaya [square] to stand against war.

Monakhov's tweet was at least in part made viral by a retweet from Mustafa Nayyem, a Ukrainian-Afghani journalist credited with catalyzing the Euromaidan protests in November of last year with a Facebook post.

RT! Давайте поможем нашим российским коллегам. @dmtrmon pic.twitter.com/J9HSZtVJfe

— Mustafa Nayyem (@mefimus) August 27, 2014

RT! Let's help our Russian colleagues.

Other users in the RuNet, like opposition activist Ruslan Levyev, also called Russians to come out and protest to their city's central square.

Никакого «назначенного времени» и места нет! Это бессрочная акция, выходите когда можете и где можете! Ближе к центру. Манежка, Красная

— Руслан Левиев (@RuslanLeviev) August 27, 2014

There's no “appointed time” or place! This is an action with no deadline, come out when you can and where you can! Closer to the city center. Manezhnaya [square], Red [square].

The hashtag storm on Twitter and other social networks undoubtedly caught the attention of Ukrainian and Western media and officials, and solicited expressions of solidarity among Russians. It is unclear if it results in any discernible action on the part of Ukrainian authorities or new sanctions for Russia from the West. Will the US and EU continue to simply be “deeply concerned”? As the situation escalates, Ukrainians turn to social networks to campaign for some kind of reaction, but the real answers might be harder to come by than a spot in the Twitter world trends.