This is the second instalment of a three-part series that examines Japan's preparedness to deal with international terrorism.
"Could it be #uk first to be attacked?" a message on Twitter said, while another said, "Maybe #France can be attacked after their #CharlieHebdo cartoons and republishing..." Yet another said: "The list is long of targets, #belgium #Germany #america #Canada #austrailia plus more but when your ready lads! May Allah protect you all."
These updates have been posted on the social media site since late January by a 33-year-old man with British citizenship, who fled to the Islamic State of Iraq and the Levant (ISIL) militant group after being sentenced to jail for stabbing a football fan with a pen. He has as many as 1,300 followers.
During the Japanese hostage crisis, video sharing sites such as YouTube were used, demonstrating how the Internet is utilized by ISIL and other emerging terrorist groups to spread their radical ideas and foster terrorism.
Some tweets, which appear to have nothing to do with terrorism, contain coded, specific instructions to carry out terrorist acts. In cyberspace, unsettling information was circulated second by second.
In January, a group of hackers believed to be affiliated with ISIL hacked the Twitter and YouTube accounts of US Central Command.
ISIL has also encouraged radical groups around the world through its digital strategy, and has taken advantage of a civil war and instability to obtain territory.
ISIL has penetrated into an empty place in the hearts of young people who feel despair and rage against society. The number of foreign fighters it has attracted is estimated at more than 20,000 from 50 countries. The possibility that some Japanese might be also inspired cannot be ruled out, observers say.
Of the foreign fighters - including those from such Asian countries as China and Malaysia - 10 per cent to 30 per cent have returned to their countries or are on their way home. The threat of terrorism posed by these returnees and individuals inspired by radical ideas has been on the rise. In January, a series of terrorists attacks were carried out in broad daylight in Paris by perpetrators shooting Kalashnikov machine guns. Similar incidents have been reported elsewhere in the world.
In addition to military operations, the United States, European nations and others are striving to monitor and block the flow of information, personnel and money related to radical groups in an effort to contain them. They are also expediting efforts to build an international mechanism to share intelligence.
Their efforts have already hit a wall. A total of 300 hours of video is said to be posted on YouTube every minute, and it is difficult to delete videos from the site because of the need for freedom of expression.
Along the borders of Syria, bogus passports are traded and immigration control is lax, encouraging illegal entry to the nation, which is racked by civil war. Elsewhere in the world, radical Islamic groups are taking advantage of poverty and other challenges facing nation-states to multiply.
Foreign Minister Fumio Kishida plans to attend an international ministerial meeting on counterterrorism to be held in Washington on Feb. 19.
Japan will take on the daunting challenge of containing terrorism together with the international community at a time when terrorism is becoming more insidious and presenting a greater threat.