President Trump's missile defense project, called the "Golden Dome for America," aims to protect the U.S. from foreign threats. But it has a steep price and has been criticized by China as threatening to increase the risks of militarizing space and a global arms race.

Trump announced the $175 billion concept in the Oval Office on Tuesday, saying it would put U.S. weapons in space for the first time and be would be “fully operational” by the end of his term in early...

An initial sum of $25bn (£18.7bn) has been earmarked in a new budget bill - although the government has estimated it will end up costing much more than that over decades.