IT WAS a holiday weekend. A bumper time for the country’s tourism industry as locals joined foreigners at seaside resorts to celebrate the Queen’s birthday, which is also Mother’s Day in Thailand.

Then, less than 12 hours apart, the resort of Hua Hin was rocked by four bombs that killed three people and wounded 24 others.

Other blasts followed, striking the island of Phuket, a world famous resort town, and Surat Thani, the jumping off point for travellers heading to the white sandy beaches of Gulf of Thailand islands such as Koh Samui.

So far the Thai authorities have not revealed who they believe were behind the attacks, which targeted popular tourist sites almost exactly a year after 20 people were killed at the Erawan shrine in Bangkok.

Even though suspicion falls on insurgents from Muslim-majority provinces in southern Thailand, the same authorities have been keen to play down a terrorist motive.

It’s a move many say is nothing more than an effort to lessen the impact on Thailand’s economic lifeline - tourism.

“It’s bad for the economy, which is limping along on one leg, and now we have these incidents,” said Ittirit Kinglek, the president of the Tourism Council of Thailand.

His views echo those of many local Thai business people who know full well the effect the attacks will have on trade.

Deadly as they were, the latest bomb attacks in Thailand were fairly small and crude devices compared to those used in recent terrorist strikes elsewhere in the world.

The bombs were most likely aimed at sending out a clear message, one that only further adds to the woes of a massive global tourism industry reeling from the effects of transnational terror.

From Turkey to Tunisia, Nice to Cairo, terrorists be they home grown or international, know exactly what the impact of their deadly trade will be on tourist economies.

With publicity the oxygen that fuels the fire of terrorist organisations, murdering innocent visitors on holiday, the softest of targets, is a brutally effective short-term strategy.

For terrorists, tourist are easy targets. Holidaymakers’ behaviour and their routes are easily predictable. As potential victims they are often unsuspecting, sometimes naive and unprotected.

Attacking tourists also guarantees acres of media coverage in the home countries of the victims, as well as in the destination where the attack took place.

Like al-Qaeda and other terrorist organisations before them, the Islamic State (IS) group especially is now specifically targeting tourists and their destinations to achieve their objectives.

As the territorial caliphate of IS in the Middle East shrinks and they find themselves militarily on the back foot, increasingly the group is switching to acts of transnational terrorism.

Sowing fear, hatred and division is one objective, but damaging economies and building political pressure inside countries is another.

In Belgium, where IS attackers bombed the Brussels airport and subway in March, killing 32 people, the economy has already suffered a nearly €1 billion (£863bn) loss in business and tax revenue.

The biggest hits were to hotels, restaurants and tourism. Concerts, carnivals and sporting events were cancelled, sapping revenue from the entertainment industry.

“Insecurity hinders tourism development and the lack of tourism development generates widespread insecurity through its economic pressures,” says Dr Yeganeh Morakabati, an analyst at Bournemouth University, who specialises in risk perception, terrorism and political conflict.

Morakabati points out that such a downward economic spiral in some societies often increases discontent, diminishes hope, generates resentment and creates an environment ripe for the recruitment of disenfranchised youth into militant groups.

This is especially the case in many developing countries heavily dependent on international tourism.

“Tourism is the only economic sector where developing countries consistently run a trade surplus,” says Lisa Mastny, a staff researcher at the Worldwatch Institute, who writes on developmental issues.

“It’s especially significant in poorer countries that have few other options and for the world’s 49 so-called least developed countries, tourism is the second largest source of foreign exchange after oil.”

This symbiotic link between terrorism and tourism became globally apparent in the wake of the September 11 attacks in the US in 2001.

Before that attack, travel and tourism was the world’s largest industry, accounting for one in every 12 jobs.

But when this massive $3.6 trillion (£2.8tr) industry went into decline after the al-Qaeda attacks, the knock-on effect extended well beyond the US, exposing the vulnerability of many countries in the developing world where lives are often devastated by derailed economies.

Security analysts point to the unpalatable but unavoidable fact that terrorism is very cost effective when directed in this way.

Take for example the attacks on nightclubs in 2002 by the al-Qaeda offshoot Jemaah Islamiah on the Indonesian Island of Bali.

For a mere $74,000 (£57,200) the terrorists effectively mounted an operation that killed 202 people and temporarily ruined the tourist industry in Bali. More recently IS spent less than $10,000 (£7,700) to finance the Paris attacks in 2015. The cost to the French economy has been enormous. Tourism is one of the largest of its sectors accounting for 7 per cent of France’s gross domestic product. France is the number one tourist destination in the world, with 83 million visitors annually and those tourists spent $45.3bn (£34.8) in 2013.

Parisians are known to be fond of saying that in August, they leave the city for a holiday and entrust the keys to the tourists. But right now far fewer tourists are taking up that offer.

In past years it could take hours to queue in popular sites like the Louvre Museum and the Eiffel Tower, but visit Paris right now and those queues are noticeably shorter.

The figures speak for themselves, with hotel occupancy falling by 12 percent in June this year, compared to June 2015. The number of flight arrivals too for the month of July decreased by 10 per cent compared to last year.

“The main reason for this fall is the fear of the risk of attack, which is weighing on a lot of foreign customers, generally from far away, particularly Asian customers who are averse to risks, who don’t know these security problems in their own countries in general, I’m particularly thinking of Japan,” says Thomas Deschamps, statistics officer for the Paris Convention and Visitors Bureau.

Some tourist economies of course seriously struggle to recover from major terrorist attacks.

Following the downing of Metrojet Flight 9268 at Sharm el-Sheikh and Egypt Air Flight 804 from Paris to Cairo, widely believed to have been the result of terrorism, Egypt’s already hard hit tourist trade has been in meltdown.

In 2010, the revenue earned by the country through tourism was estimated to have been in excess of $12bn (£9.3bn) accounting for 11 per cent of the country’s GDP, more than 14 per cent of its foreign exchange reserves. By last year that figure was already just fewer than half that amount, at $6.1bn (£4.7bn).

Where Egypt had 15 million visitors in 2010, in the first quarter of 2016 it now barely attracts 1 million tourists.

Despite all this, tourism remains one of the biggest economic sectors on the planet. In the EU alone there are as many people working in tourism as there are in the car manufacturing, industry, or agriculture.

As certain destinations lose their innocence, this fear of terrorism is rapidly dividing the world into winner and loser countries.

While places like Spain, Greece and Italy are profiting, in Turkey, Egypt, Tunisia and Morocco, small family-owned companies and large hotel chains alike are going under.

To take Tunisia alone, the livelihoods of roughly 2 million people there depend on tourism. The turmoil that followed the Arab Spring was already keeping some foreigners away, but it wasn’t until the dual attacks in 2015, one in March in front of the Bardo National Museum in Tunis and another in June on the beach in Port El Kantaoui, that revenues from tourism plummeted by 35 per cent.

Depressing as such statistics are, terrorism’s impact on tourism is nothing new. It’s now 30 years since both the Palestinian Liberation Front (PLO) hijack of the Achille Lauro cruise liner, and the suicide grenade and gun attacks by the Abu Nidal group which killed 16 people at Rome and Vienna airports.

In many countries tourism has often shown great resilience to such setbacks. Some analysts, like Morakabati, suggest no two terrorist attacks leave the same “data fingerprint” in terms of their impact on tourist arrivals.

An attack might create a sudden fall, followed by a quick recovery; a sudden fall, followed by a gradual recovery; a sudden fall in the number of arrivals leading to a permanent reduction in tourist flows; a slowdown in the growth of arrivals; or no impact at all.

According to the sober perspective of statisticians and risk analysts, it’s important they say that as individual tourists we keep the threat of terrorism in context. Tragic as it is, the number of people killed remains a tiny proportion of the billions who travel safely.

Just as terrorism is a force for good, which helps people of different countries and cultures understand each other better, so terrorism remains a corrosive force, determined to do the opposite.

Its power to wreak human and political havoc with the minimum of resources can never be underestimated.

In 2004, at an operational cost of less than $1,000 (£770) al-Qaeda bombed Spanish trains and succeeded not only in its objective of punishing the Spanish people and government for their support of the war in Iraq, but also in achieving a Spanish pull-out from the American-led coalition in Iraq. This in turn ultimately led to a change in the Spanish government, as the Socialists were swept to power in the wake of the bombings.

It’s precisely for reasons like this that tourism and “soft targets” will always be in the terrorists’ sights, especially in the most vulnerable and fragile of countries and economies.

Overall the sense that travellers worldwide are under attack is deepening, even if the risks to the individual tourist remain extremely low.

Last week the world’s biggest holiday company, Tui (owner of Thomson and First Choice) reported “lower demand due to geopolitical events” in Europe and beyond.

In security terms only a sea change in how individuals, businesses and governments think about and combat terrorism will provide any degree of real protection.

Citizens of the places where terrorist attacks occur must, of course, endure daily fear about whether they will become a statistic in the course of going about their daily business.

This weekend Thailand was on edge and police were continuing their search for the suspects behind the bomb blasts of the last few days.

If the Muslim rebels in the south were to blame, it would mark a major expansion of their secessionist campaign that has been concentrated in their heartland and rarely targets foreigners.

Famed for its idyllic islands and Buddhist temples, Thailand is a tourism powerhouse and was hoping for a record 32 million visitors this year. Only time will tell the extent to which its tourism industry has been damaged and reveal its capacity to recover.

“This incident will remind all Thais that there are still ill-intended people in the country,” Prayuth Chan-o-cha, Thailand’s prime minister, said in a televised speech on Friday.

Those “ill- intended people” are not restricted to Thailand. Tourism worldwide will doubtless continue to feel their malign presence for some time to come.