France, April 25 -- US President Donald Trump has defied international norms on the nascent field of deep-sea mining, signing an executive order expanding the practice for rare earth minerals in domestic and international waters.

White House aides say the initiative could see US operations scoop up more than a billion metric tons of mineral-rich deep-sea nodules, and pump hundreds of billions of dollars into the American economy.

But the move to disrupt ocean floor ecosystems to extract cobalt and other minerals flies in the face of environmental group concerns and the controls set by global regulators at the International Seabed Authority.

Since the 1990s, the group has sought to set ground rules for the burgeoning industry's extracti...