Mapped: Terror threat around the world
Belgium is just one of more than 40 countries around the world where the threat from terrorism is rated "high" by the Foreign Office. 
The country had the highest terror threat level long before the deadly bomb attacks on a metro station and airport in Brussels, its capital. The Foreign Office website states: "There is a high threat from terrorism. Attacks could be indiscriminate, including on public transport and transport hubs and in other places visited by foreigners. Brussels hosts a number of international institutions (EU and NATO) and government and foreign embassy buildings which are sensitive locations."
Following Tuesday's attack, it adds: "The Belgian threat level is Level 4 – a serious and imminent threat. You should remain alert and vigilant, stay away from crowded places and avoid public transport at this time."
Other countries where the threat from terrorism is rated "high" include France. The Paris attacks in November, in which 130 were killed, were the deadliest on French soil since the Second World War. 
"High profile terrorist attacks have taken place in Paris in 2015 and other smaller attacks have taken place across France," says the Foreign Office website. "On 7 January 2015, terrorists attacked the ‘Charlie Hebdo’ offices. On 9 January 2015 there were further attacks at a Jewish supermarket in Porte de Vincennes, Paris, and a police officer was shot dead in Montrouge. On 21 August 2015 there was a terrorist attack on the Amsterdam to Paris high speed Thalys train service. On 13 November 2015 terrorist attacks killed 130 and injured hundreds more at multiple sites across Paris."
The terror threat is also "high" in Egypt, where a Russian aircraft was bombed last year, Tunisia, where 30 Britons were killed in a massacre last summer, Indonesia, Russia, Myanmar, Kenya, the Philippines and Colombia, Turkey, Thailand and Australia.
The inclusion of much of the Middle East, including Iraq, Saudi Arabia, Yemen, Syria, Lebanon, Israel and Afghanistan, will come as no surprise.
The Foreign Office uses four ratings when judging the threat of a terrorist attack in its travel advice: high, general, underlying and low.
Countries where the terror threat is low include Iceland, Bolivia, Ecuador, Poland, the Czech Republic, Switzerland, Hungary, Vietnam and Japan.
The UK terror threat level, assessed by MI5, is more fluid, with five categories ranging from "low" to "critical". The UK terror threat level is currently "severe", the second highest rating.
Destinations with a "high" threat of terror:
Afghanistan
Algeria
Australia
Bahrain
Bangladesh
Belgium
Burma (Myanmar)
Cameroon
Chad
Colombia
Egypt
Ethiopia
France
Germany
India
Indonesia
Iraq
Israel
Ivory Coast
Jordan
Kenya
Lebanon
Libya
Malaysia
Mali
Mauritania
Morocco
Niger
Nigeria
Pakistan
Palestinian territories
Philippines
Russia
Saudi Arabia
Somalia
Spain
Syria
Thailand
Tunisia
Turkey
UAE
Western Sahara
Yemen
Vocabulary:
1. Capital - (noun) The city or town that functions as the seat of government and administrative centre of a country or region.
2. Terrorism - (noun) The unlawful use of violence and intimidation, especially against civilians, in the pursuit of political aims.
3. Indiscriminate - (adj.) Done at random or without careful judgement.
4. Institution - (noun) An organization founded for a religious, educational, professional, or social purpose.
5. Alert - (adj.) Able to think clearly intellectually active.
6. Vigilant - (adj.) Keeping careful watch for possible danger or difficulties.
Discussion:
1. What is the first thing that you think of when you hear the word ‘terrorism’?
2. In your own opinion, what makes a country vulnerable to terrorism?
3. Do you think it will be safe for people to travel despite the terrorism threats globally?
4. Why do people commit terrorist acts?
5. What do you believe is the best way to deal with terrorism?