The third Nuclear Security Summit (NSS) kicked off on Monday, aimed at preventing nuclear terrorism around the globe.

Leaders from more than 50 countries and international organizations have gathered here to assess past achievements in safeguarding global nuclear security and to seek more actions in preventing nuclear material falling into the wrong hands.

On the first day of the event, participating countries presented their national statements on nuclear security, and then proceeded to discuss what they would do and how they would cooperate at the international level.

A plenary meeting was held after the two-day event officially opened Monday afternoon.

Addressing the opening session on Monday afternoon, Dutch Prime Minister Mark Rutte stressed the goal of the summit is to discuss how to prevent nuclear terrorism during the summit.

"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," he said.

United Nations Secretary-General Ban Ki-moon said that the primary responsibility lies with national governments to prevent non-state actors and terrorists from acquiring the most devastating weapons.

"But international cooperation and assistance are indispensable," the UN chief said, calling on countries to do more to prevent and detect unauthorized acquisition of material outside of regulatory control.

The NSS 2014 seeks to reduce the amount of dangerous nuclear material in the world, improve security of all nuclear material and radioactive sources, and step up international cooperation.

The summit has become an important platform to address nuclear security issues since its first meeting in Washington in 2010. The second meeting was held in Seoul in 2012.

According to the NSS 2014 website, Tuesday's event includes a meeting where leaders will discuss the future of the NSS process.

This summit will conclude on Tuesday with a press conference jointly held by Rutte and the U.S. President Barack Obama, who will chair the next nuclear security summit in Washington in 2016, the website said Monday.