09/15/2010 -Both the number of terrorism attacks and arrests have decreased for the second straight year across continental Europe as the percentage of successful prosecutions rose, according to a report from the European Union's police office.

The number of terrorist attacks fell by 33 percent from 2008, while the number of individuals arrested on terrorism-related charges also dropped by 22 percent,according to Europol's TE-SAT 2010 (.pdf), which analyzes Europe's terrorism situation and trends. The differences are even more pronounced if the number of attacks and arrests are compared to 2007 data. Attacks are down by approximately 50 percent while arrests have fallen by 30 percent in two years across the continent. (The report does not include quantitative terrorism data from the United Kingdom, "because of differences in the statistical criteria applied.")

Most terrorist attacks reported by six EU member states were the work of ethno-nationalists or separatist groups. All 237 separatist attacks occurred in either Spain or France, primarily the work of ETA or Corsican terrorist groups, respectively. Even though separatist attacks occurred more often than any other type of terrorist attack, the percentage still fell 40 percent from 2008.

Representing only a tiny percentage of attacks, the type of terrorism that saw the most dramatic rise from 2008 to 2009 was left-wing and anarchist terrorism. Attacks by these groups—mainly active in Spain, Greece, France, and Italy—rose by 40 percent, although these perpetrators primarily attacked private property through arson.

The terrorism category least represented for the second year straight was Islamist terrorism. The sole event occurred last October when a Libyan national detonated an explosive device outside of an Italian military barracks, injuring one soldier and badly burning himself. There was no reported act of Islamist terrorism inside continental Europe in 2008, although one did occur in the United Kingdom,according to last year's report (.pdf).

Nevertheless, the report notes that Islamist terrorism is still considered a threat.

"Similar to previous years, Member States reported that the threat remains real and serious, despite the fact that none of them, with the exception of Italy, had been directly affected by an Islamist terrorist attack."

Europol also points to Christmas Day's botched terrorist attack on board an airliner heading to Detroit from the Netherlands as well as the year's 110 arrests as evidence the threat from jihadists remains real and deadly.

According to the data, 587 suspected terrorists were arrested in total, the majority for terrorist activities related to separatism, followed next by jihadism. But most were arrested based on suspicion that the suspect was a member of a terrorist organization. "Almost 30 percent of the arrests were related to attacks and 17 percent to the financing of terrorism," reports Europol. "Other activities of which the suspects were accused include propaganda and facilitation."

The report also details the number of terrorism cases tried across the European Union. In 2009, 391 individuals were tried on terrorism charges and 125 court decisions were handed down. The prosecution prevailed a majority of the time, with 17 percent of verdicts ending in acquittal, down from 23 percent in 2008. According to Europol, separatists (66 percent) and Islamists (22 percent) were the most represented kind of terrorists in the cases tried last year. Those convicted of a terrorist-related charge in Europe received an average penalty of five years behind bars.

♦ All graphs were taken from Europol's TE-SAT 2010: EU Terrorism Situation and Trend Report