Like many major cities, London has always been vulnerable and an attack was merely a question of when and not so much if.
Sydney, for example, will always be on the radar screen of the terrorists because of Australia's strong support of the US attack in Iraq.
Hours after the blasts in central London, an unknown group calling itself the al-Qaeda of Europe claimed responsibility through a website. Although the details of how the bombings were carried out are still sketchy, it appears to be well-coordinated.
While terrorists can strike any time, anywhere and at anyone, one pattern that has emerged over the years is their preference to strike during summer.
Summer has just started in Europe with the tail end in September, when the weather gets cooler again. Analysts believe that with light clothing, terrorists are able to move and operate easier.
Bulky clothes are often avoided by terrorists as they believe that it would hamper their movement while unpredictable weather, particularly during winter, could hinder their bombing operations.
The sunny weather of summer is regarded as the best time for any covert operations, especially during lunch time when the crowd becomes big, to ensure maximum destruction.
During this holiday season, people often let their guard down and tend to congregate in large numbers, whether at the park or shopping mall. Public transport is also at its peak.
At the Atlanta Olympic Games on July 27, 1996, the explosion of a pipe bomb in a paper bag killed one person and injured over 100 people.
September has also been a popular month for previous terrorist attacks. At least seven high-profile attacks were carried out in recent years in September.
On Sept 5, 1972, 11 Israeli Olympic team members were killed in the Munich Games;
On Sept 4, 2000, a car bomb exploded outside an apartment in Dagestan, Russia, which killed 64 people;
On Sept 8, 2000, another bomb exploded in a nine-storey apartment in Moscow, killing 94 people with 150 injured;
On Sept 13, 2000, a bomb went off in an apartment near the Kremlin, killing 118 with 200 injured;
On Sept 11, 2001, the attack on the World Trade Centre in New York;
On Sept 4, 2004, more than 300 people, mostly children, were killed following a siege by militants who took over a school in Beslan, Russia.
Even in South East Asia, the Jemaah Islamiah terrorists picked Sept 9, 2004, to launch an attack in Jakarta which killed nine people and injured over 100.
September will remain a black month for terrorists in many ways. For older Palestinians, they remember the formation of the Black September terrorist group, so named because it was formed in that month after radicals felt betrayed by Jordan where they had sought refuge from the Israelis.
For ordinary people living in major Western cities, they will have to live with the terror fear every day. They have little choice but to use the same subway and buses, which are soft targets, to commute. The threat of these terrorists striking again will always be there.
When these terrorists attack, they do not care whether their victims are Muslims or Christians, so long as they can inflict the greatest damage.
As politicians in the West renew their commitment to fight terrorism, they cannot ignore the fact that until they seriously re-think their policies in West Asia, including solving the problems in Palestine, no amount of security measures can help them ward off such attacks.