The primary terrorism risk stems from Switzerland's extreme left-wing and radical environmentalist groups, who stage peaceful demonstrations, but also small attacks with explosive or incendiary devices against banks and businesses in bigger cities. Such attacks are most likely around the dates of the Davos World Economic Forum in January of each year. Extreme right-wing and skinhead groups, operating mainly in the German-speaking parts of Switzerland and especially in the cantons Schwyz, Zurich, St Gallen, Bern and Aargau, are likely to engage in vandalism and isolated acts of arson or use of small explosive and incendiary devices, most likely against immigrant-related and Jewish-related targets. In May 2007, the Hekhal Hanes synagogue in Geneva was destroyed in an arson attack, while in March 2008, 12 men disrupted a party being held by Turkish people in Biel, causing some property damage and injuring two people. Typical targets are restaurants, religious sites and community centres, but also bars and centres affiliated with extreme left-wing groups. With regards to both right-wing and left-wing militants, no sustained terrorist campaign is likely, but rather small-scale attacks carried out by individuals or small cells. The likelihood of an Islamist terrorist attack in Switzerland is still very limited, but the risk has increased in recent years. Until recently, Switzerland has been a logistical base for Islamist militants, while its geopolitical neutrality discouraged attacks on Swiss territory. This mechanism is no longer effective, due to a radicalisation risk of a minority of Swiss Muslims. Muslim immigrants make up some 4.5% of the population, living nearly exclusively in bigger cities such as Zurich, Bern, Geneva, Basel and Luzern. While the Muslim population is overwhelmingly peaceful, in 2006 the police arrested a dozen suspects who allegedly plotted to shoot down an El-Al plane taking off from Geneva Airport. The plot was far from being realised, but it exemplifies the risk of isolated cells or individuals staging attacks. However, there is no evidence of other plots up to today; the intent to attack Swiss targets is small and capability of emerging cells is likely very limited.