Dutch prime minister Mark Rutte on Monday afternoon formally opened the Nuclear Security Summit in The Hague with a short speech underlining the need to head off nuclear terrorism.

Much progress has been made in recent years but much remains to be done, Rutte said.

‘All our discussions today and tomorrow will focus on one question: how to prevent nuclear terrorism?,’ Rutte said.

‘Or to be more precise: how can we make sure that nuclear materials won’t end up in the hands of terrorists and that nuclear material is used more efficiently and stored more securely.’

Closed doors

The meeting, involving 53 heads of state, is taking place behind closed doors. The leaders of the G7 will also meet at 18.30 in the prime minister’s official residence, Catshuis, to discuss how to deal with the Russian annexation of Crimea.

Earlier on Monday, US president Barack Obama spent some 90 minutes in Amsterdam, touring the Rijksmuseum and holding informal talks with Rutte.

According to website nu.nl some 50 anti-nuclear weapons campaigners were arrested at The Hague’s main railway station for attempting to get close to the World Forum where the summit is taking place.

Four others were arrested for holding a protest in the pond outside the Dutch parliament. ‘We chose to stand here because it was difficult for the police to reach us,’ one told nu.nl.

The summit involves the biggest security operation ever mounted in the Netherlands.