Over the past four years, U.K. forces say they have foiled 13 terrorist plots

London has often been the target of terrorist attacks, from IRA campaigns in the 1970s and ’80s to more recent Islamist plots.

On July 7, 2005, four al-Qaidainspired British bombers blew themselves up on three subway trains and a bus in London, killing 52 people.

British security forces say they have thwarted 13 terror plots over the past four years, but in recent years the U.K. has largely been spared major international terror attacks such as the ones seen in Belgium and France.

Last year, a far-right supporter shot and killed British lawmaker Jo Cox, who had campaigned for the U.K. to remain in the European Union. Prior to that, an attacker claiming to be motivated by Syria stabbed three people at a London subway station.

The most gruesome recent attack occurred in 2013 when two Muslim converts of Nigerian descent attacked Lee Rigby, a British soldier who was walking down the street. The men ran Rigby down with their vehicle and then used a cleaver to hack him to death as bystanders watched in horror.