
The annual Cobra Gold military exercise began in Thailand on Tuesday.

The event sees thousands of US troops taking part in a series of grueling and garish tasks all in the name of survival.

Twenty-nine other nations are also attending the largest event of its kind in the Asia-Pacific region, which teaches troops how to survive in extreme conditions in the jungle.

Around 4,500 members of the US armed forces will be taking part in drills on land and sea. Alongside them will be there counterparts from Singapore, China , Japan , India, South Korea, Indonesia and Malaysia.

The training is now in its 39th year and lasts for 10 days.

The US Marines got stuck into the drills on Tuesday as they lined up to drink the blood of a decapitated cobra - which is said to be a good source at re-hydrating the body should drinking water not be available during a jungle mission.

Some of the pictures show the bright red blood being dripped onto their tongues.

US Marines are pictured drinking raw cobra's blood offered by a Thai Marine during jungle survival training as part of the multinational joint military exercise Cobra Gold 2020 at a Navy camp in Chanthaburi province, Thailand

A US Marine, right, reacts next to a Thai Marine, left, after killing a chicken with his bare hands during jungle survival training

Tens of thousands military personnel from 29 countries, led by the US troops, take part in the largest annual multinational military exercise in the Indo-Pacific designed to enhance regional security cooperation

A US Marine bites the tail of a cobra after killing it during jungle survival training

A US Marine tastes a live gecko during jungle survival training after skinning the reptile

A Thai Marine demonstrates to US Marines how to eat a live scorpion during jungle survival training

A Thai Marine demonstrating how to handle a cobra. Thai soldiers showed the troops how to properly kill the snake first

A Thai Marine lets US Marines touch a snake during a jungle survival training as part of the Cobra Gold military exercise

A Thai Marine places a snake around the shoulders of a US Marine. The exercise is aimed at drawing the U.S. closer to allies in Southeast Asia

A Thai Navy instructor holds up two cobras as he passes on his knowledge about how to catch and kill the venomous snakes

Some of the soldiers stuck out their tongues tentatively. Many squeezed their eyes shut, while their comrades looked on and laughed - with some even taking cellphone pictures and video to capture the moment.

Thai soldiers showed the 10,000 competing troops how to properly kill the snake first.

A number can also be seen almost celebrating as they guzzle down the snake blood - described as 'fishy' tasting - in front of their jubilant comrades at Akatotsarot Camp, in Phitsanulok, Thailand.

US Marines queued up to drink the blood of a cobra - with some more enthusiastic about the prospect than others

4,500 members of the US military are taking part in the exercise, which ends on March 6

Some tentatively presented their tongues with their eyes tightly shut, as their comrades looked on and laughed

US Marines watch a cobra during jungle survival training as part of the multinational joint military exercise

A challenge with a sting in its tail - A U.S. Marine prepares to eat a scorpion during the jungle survival exercise in Thailand

Marines were forced to eat a variety of creatures indigenous to densely wooded areas, including scorpions and tarantulas

Being stuck in a jungle is a real-life situation that the troops might be stuck in at some point in the future and the war drills prepare them for that by completing the trials

Marines were also forced to eat a variation of other creatures indigenous to densely wooded areas, including scorpions, tarantulas and other jungle bugs.

There are three major components of the exercise: military field training, humanitarian assistance and disaster-relief training.

The marines were also taught how to find water in jungle vines and identify edible plants by military trainers.

Soldiers learn to de-fang tarantulas before eating them, as well as consuming lizards and other creatures indigenous to densely forested areas.

There are also vegan options too with the jungle being rich in fruit and other lush, edible vegetation.

A Thai Marine demonstrates how to catch snakes to US Marines during jungle survival training

Cobra blood is said to be a nutritious and hydrating option, should clean drinking water not be available in a jungle disaster

A US Marine handles a tarantula. The troops learned how to de-fang tarantulas before eating them

A Thai Marine instructor demonstrates to the U.S. Marines how to catch a cobra during the jungle survival exercise

The 11-day exercise, called Cobra Gold, involves soldiers from Thailand, the US, Singapore, Indonesia, Japan and South Korea

A US Marine is offered to taste a live gecko by a Thai Marine during jungle survival training

There seems to be more than enough geckos to go around at the 11-day training in the Thai jungle

Other exercises include military field training, humanitarian assistance and disaster relief drills across the next five days, before the closing ceremony on March 6.

A 2014 army coup in Thailand tested ties with Washington, which urged a return to democracy and scaled back military aid.

But the two countries have upped their engagement under President Donald Trump, who has taken a softer stance on human rights issues and even embraced Thai junta chief Prayut Chan-O-Cha in the White House.

A Thai Marine demonstrates how to eat a live tarantula during jungle survival training

A Thai Marine demonstrates how a gecko bites, although he will later get his own back as he eats the reptile

The Marines also learn how to find and eat other jungle creatures, like geckos, pictured, and gibbons.

A Royal Thai Marine instructor shows US Marines different types of snakes during jungle survival training and demonstrates how to catch a cobra to US Marines