We will define the extreme left as groups willing to use violence against people and property in support of traditional left-wing objectives, such as the challenging of capitalism, imperialism and nationalism.
The reasons for the increase of left-wing violence is very similar to the reason for the rise of right-wing violence. The 2008 financial crash allowed the extreme right to blame the international financial class and appeal to nativist politics, while it allowed the extreme left to agitate in favour of the rights of the workers of the world against that same financial elite. Furthermore, the two wings feed on each other – the extreme-left justifying its actions as ‘antifa’, antifascism, while those on the right define themselves as resisting a Marxist revolution. When one side increases in prominence, the other is required to increase their efforts correspondingly, and both sides have become more polarised as distrust in mainstream political parties increases. Many incidents of left-wing violence occur at right-wing protests, and vice-versa.
One relatively unique trait of extreme left violence is the level of solidarity displayed between different groups. Although the extreme right in one country is often happy to point to right-wing successes in another as a sign that their politics is vindicated, often groups cannot stand one another, in keeping with their often insular perspective. On the left the actions of one group in one country will often be echoed, in solidarity, by the actions of another elsewhere.
Italy’s recent history of left-wing violence contains examples of this. In 2013 the CEO of a nuclear engineering company was kneecapped in Geneo by Italian left-wing extremists belonging to a cell of the Informal Anarchist Federation-International Revolutionary Front. (FAI or sometimes IAF). The cell was named after Olga Ikonomidou, one of eight Greek anarchists imprisoned in Greece. They promised more attacks to be perpetrated by terrorist cells named after Ikonomidou’s fellow detainees.
In a separate incident, a German left-wing group burnt several cars outside a German telecoms company in protest of Greek austerity and the imprisonment of another left-wing activist, arrested for terrorist activity, Stella Antoniou. The cell is named after Lambros Foundas, a Greek anarchist shot by police during a protest.[9
These expressions of, and actions to support, solidarity between different extreme left-wing organisations is something to watch; while the right either has no interest in uniting or has failed to do so, the far left has a long history of cooperation across borders.
Germany shows the triangular relationship between Islamist extremism, right-wing extremism and left-wing extremism. A report by the German intelligence services observed that all three forms of extremism had increased dramatically between 2015 and 2016.An increased level of violence by one is usually met by an increase in violence by the other two.
However, Germany’s left-wing violence also demonstrates that the extreme left is not just reacting to the struggle between Islamofascists and the regular European variety of fascists. Recent violence between left-wing groups and the police have focused on domestic issues of housing and class. We should not make the mistake of focusing on left-wing groups as always a reaction to right-wing violence, though this is a trend we will see increase.
Greece and Sweden have the most active left-wing extremist groups in Europe today. Sweden’s Revolutionary Front is actively involved in violent combat with far-right groups, with one member notoriously stabbing a neo-Nazi in the back at a protest in 2013. They are some of the most overtly militant left-wing extremists active in Europe today. At the same time they are relatively unknown outside Sweden, and are careful to conceal their identities, presumably out of fear of reprisals from far-right groups as well as arrest by the Swedish police. Sweden is currently struggling to deal with a rise in far-right violence and a new and large immigrant population, and the Revolutionary Front making sure the far left is involved in the struggle over Sweden’s political culture.However, as with many extreme left wing groups the Revolutionary Front was active before the spike in nationalism and the social tension caused by the migrant crisis of the last couple of years.
Greece has an extensive history with far-left groups, both in opposition to the neo-Nazi Golden Dawn organisation and involved in a wider struggle against capitalism.
In April 2012 a far left organisation took credit for a bomb left on the Athens Metro. They objected to the Metro’s closure during an anti-austerity protest, which they viewed as a betrayal of the working class. Before this, the Conspiracy of the Fire Nuclei group were involved in several bombings and arson attacks, including posting letter bombs to European heads of state. The organisation has been proscribed as a terrorist threat by the US State Department. In short, Greece’s experience of left-wing violence shows that the phenomenon has been present for much of the 21st century, rather than only reacting to the far right.This does not mean that the pattern of left-wing right-wing violence is not playing out in Greece as well. The murder of Pavlos Fyssas by members of neo-Nazi Golden Dawn members, which led to police investigations and a foiling of the group’s parliamentary ambitions, also led to reprisals from the far-left Fighting People’s Revolutionary Power. Members of the organisation shot dead two members of the Golden Dawn, and chillingly declared every member of Golden Dawn as ‘legitimate’ targets for execution.
Britain has avoided domestic left-wing extremism this century (with some exceptions), but thanks to modern technology’s ability to transmit ideology across national boundaries we should not become complacent. Just as Thomas Mair was radicalised by American far-right groups it is far from inconceivable that violent continental organisations on the other side of the political spectrum could have the same effect on impressionable minds in the UK.
Left-wing extremism, fed by ongoing economic dissatisfaction as well as reaction to the even more prominent European far right, will likely remain a European security issue for years to come. However, as with right-wing extremists, left-wing extremists are probably benefiting from police and intelligence services’ focus on Islamic extremism as the main security threat. Looming European elections in France, Germany and the Netherlands will show increased public support for the far-right politics of Le Pen, Petry and Wilders, not the far-left ideologies of Syriza in Greece and Podemos in Spain. This political trend will provoke reaction, with left wing groups organising in opposition. While we must hope both sides use words not violence, historically extremists on both sides will make themselves felt.
 http://actforfreedomnow.blogspot.co.uk/2011/02/text-by-stella-antoniou-arrested-on.html and