Nicknamed "The Human Weapon", Du-Ri also played in the 2002 World Cup, but as a forward, and has since converted to defence and is now noted for his willingness to join attacks.

BBC: South Korea defender Cha Du-Ri seals Celtic switch

Traditional rules of engagement stipulate that a human must decide if a weapon is to be fired.

ECONOMIST: Robots go to war

" Since string made possible everything from warm clothing to ocean-going boats, it served as "the unseen weapon that allowed the human race to conquer the earth.

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What it lacked was human intelligence, the single most important weapon in the arsenal of counter-terrorism.

BBC

The robot sentry, the Samson Remote Weapon Station, could function without human intervention, says David Ishai of Rafael, its Israeli manufacturer, based in Haifa.

ECONOMIST: Robots go to war

In early human history, the dagger was a more common weapon, but about 5, 000 years ago, people learned to produce longer copper and bronze blades, and the sword became more common.

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