Demonstrators hold placards calling for government funds to be spent on the NHS and climate change, as they attend an anti-war and anti-trident demonstration near the Houses of Parliament in central London on July 18, 2016.
Prime Minister Theresa May warned Monday that the threat from nuclear weapons was increasing as she pressed MPs to approve the replacement of the ageing submarines that carry Britain's nuclear arsenal. MPs will vote Monday evening on whether to approve the construction of four new submarines to carry the Trident missile system and their nuclear warheads, at a cost of £41 billion (49 billion euros, $54 billion). / AFP / DANIEL LEAL-OLIVAS        (Photo credit should read DANIEL LEAL-OLIVAS/AFP/Getty Images)