In 1994, some soldiers from the British Army were flying in a helicopter called a Lynx. They were flying over a place called Northern Ireland, which is a part of the United Kingdom.
But then, something bad happened. People who were fighting against the British government shot a missile at the helicopter, and it hit the Lynx. The helicopter crashed, and four of the soldiers inside were killed.
This was a very sad event, and people were very upset. The British government wanted to figure out who did this and why it happened. They investigated and found out that a group called the Provisional Irish Republican Army (IRA) was responsible for the attack. The IRA was a group that had been fighting against the British government for a long time because they wanted Northern Ireland to become its own separate country, instead of being a part of the UK.
Because of this incident, the government decided to tighten security in Northern Ireland to try and stop these kinds of attacks from happening again.