Chinese President Xi Jinping wrapped up a productive trip to the U.S. capital and departed for home on Friday evening after attending the fourth Nuclear Security Summit (NSS).

He took part in all the activities on the NSS schedule, including a dinner hosted by U.S. President Barack Obama at the White House on Thursday evening, an opening plenary on Friday morning, as well as a working lunch, a scenario-based policy discussion and a closing session in the afternoon.

In a speech delivered at the opening meeting, the Chinese president urged countries around the world to increase national input and expand international cooperation so as to further firm up the global nuclear security architecture.

The 2016 NSS, which was the last in its current format, gathered leaders and envoys from 52 countries and four international organizations. A communique was released along with five action plans.

On the sidelines of the summit, Xi attended a leaders' meeting of the P5+1 mechanism, which comprises the five permanent members of the UN Security Council -- Britain, China, France, Russia and the United States -- plus Germany and reached a historic agreement with Tehran in July over its controversial nuclear program. 

He also held bilateral meetings with Danish Prime Minister Lars Loekke Rasmussen, Obama, South Korean President Park Geun-hye and Argentine President Mauricio Macri. Following his meeting with Obama, their first so far this year, the two sides issued two joint statements, respectively, on nuclear security and climate change.

Xi arrived in Washington on Wednesday evening from Prague after rounding off a successful trip to the Czech Republic, the first state visit to the Central European country by a Chinese head of state in 67 years.