According to the U.S. State Department, one of several government or commercial organizations that try to count terrorism activity, found that terrorist violence was up by a third in 2014 (to 13,500) mainly due to ISIL in Syria and Iraq and Boko Haram in Nigeria. The number of terrorist related deaths nearly doubled (to 33,000) and the number of kidnappings nearly tripled (to 9,500).
ISIL and Boko Haram were heavily into mass killings and mass abductions in 2014. There were consequences and both ISIL and Boko Haram were less deadly in 2015. Both organizations suffered from more retaliation and were more often on the defensive in 2015. The degree of savagery ISIL and Boko Haram exhibited in 2014 motivated more nations and groups to fight back. While terrorist attacks occurred in 95 countries some 6o percent of it occurred in just five countries (Iraq, Pakistan, Afghanistan, India and Nigeria). Some 80 percent of terrorist related deaths occurred in just six countries (Syria, Iraq, Pakistan, Afghanistan, India and Nigeria).
This sort of thing has happened before. The last time was in Iraq when, in 2005-7 when worldwide terrorism deaths (of civilians) remained at 71-74,000 a year. Suddenly, in 2008, it dropped 24 percent. About half that decline came from the sharp drop (by about half) of terrorist attacks in Iraq. Deaths in Iraq fell even more sharply (73 percent). But Iraq, which was getting most of the Western media attention for terrorism, only accounted for a third of the total terrorist attacks in 2008, and only ten percent of the terrorism related deaths. Even during the peak years (2006-7), Iraq only accounted for 20 percent of worldwide deaths. It turns out that there's a lot more terrorism going on than the mass media reports on. Can't blame them, though, because, when you start digging, you find that there's a lot of violence in the world that is terrorism related. Sort of, or at least somewhat.
After September 11, 2001, it suddenly became important to count terrorist attacks accurately. That was the only way to get a sense of how large, and where, the problem was. But there were some difficulties. Take organized crime, for example, where terrorism is just another tool. Terrorism is regularly practiced by organized criminal groups. That's how the famous ones, like the mafia, or the Russian or Colombian gangs, make money and maintain discipline. What separates "terrorist organizations" from criminal gangs is ideology and goals. Organized crime groups just want to make money. Islamic terrorists, however, have other goals; like imposing Islam on the entire world. Making money using criminal methods is a means to an end for them, not an end in itself. Keep in mind that terrorist acts are a constant, and most of these actions are carried out by criminals in pursuit of a payday. Political or religious terrorists are using similar terrorism to either attract attention, as a fund raising tool, or a weapon to win concessions from governments.
So we have terrorism divided by goal (power or money). But much of the terrorism in the world is mainly about power (getting it, or holding on to it.) In many parts of the world, political power is obtained, and retained, by using gangs of terrorists. Nothing new there, the ancient Romans, and many before them, used political gangs, and terrorism, to achieve political goals. This works in democracies as well as dictatorship. In Iraq Saddam had street gangs to keep hostile Iraqis under control.
In many parts of the world, political and criminal (just for the money) terrorism are combined, as an extortion/vote getting act. Analysts often have to flip a coin to decide which act of terrorism is religious or ideological and which is simply gangsters taking care of business.
While most of the terrorism committed after 2001 was carried out by Islamic radicals, they have found allies in existing radical leftist groups. For example, in Okinawa, a group calling itself the "Revolutionary Army" set off three pipe bombs during one week in 2007. The same group claimed responsibility for similar attacks in 2002. Leftist radicals are much more widespread than the Islamic kind and have been around for over a century. The most successful leftist terrorists were the anarchists, a 19th century movement that killed several heads of state, and hundreds of other officials, before being wiped out by the more bloody minded communists before World War II. The communists were radical leftists, until they established the Soviet Union in 1923. After that, communism was noted chiefly for its highly effective police state methods, and support of terrorism by other groups. The Soviet Union was a major supplier of training, weapons and money to leftist terrorists. With the collapse of the Soviet Union in 1991, that support went away, but the leftist, and even Islamic, groups the Soviets had supported, did not. While there are few Soviet trained terrorists out there any more, there are still plenty of radical groups.
The Japanese ones support a number of causes, from the establishment of communist dictatorships, to the destruction of the United States, protectionism (no "economic globalism"), the status quo in general and so on. The groups operating in Okinawa want U.S. troops out of Japan. The United States is a convenient enemy for leftists, many of whom oppose free markets, democracy (and a lot more besides) and anything that will get a mention in the mass media.