Four peace activists scaled a crane next to the Houses of Parliament in London Tuesday to protest government plans to update the Trident nuclear weapons system. The Greenpeace campaigners clambered up the crane next to Big Ben and unfurled a 50-foot (15-meter) banner suggesting Prime Minister Tony Blair loved weapons of mass destruction. "We can't oppose proliferation of WMD if we're building them at home," one of the activists on the crane, Cat Dorey, said. Lawmakers are scheduled to take a key vote Wednesday on replacing Britain's fleet of nuclear armed submarines. Commons Deputy Leader Nigel Griffiths resigned Tuesday so he could vote against the government in the Trident vote. Greenpeace said the activists would stay perched on the crane until Wednesday's vote.