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.

President Donald Trump is expected to announce on Tuesday the concept he wants for his future Golden Dome missile defense program

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.