MUNICH -- The 54th Munich Security Conference (MSC) closed on Sunday, leaving "a lot more work ahead" in addressing global security issues.

Under the motto of "To the Brink, and back?", over 500 participants including UN Secretary-General Antonio Guterres, U.S. Defense Secretary James Mattis, Russian Foreign Minister Sergey Lavrov, British Prime Minister Theresa May and NATO Secretary General Jens Stoltenberg, attended the three-day major annual gathering for international security issues.

"When I opened the conference on Friday, I hoped we could delete the question mark from the motto," MSC Chairman Wolfgang Ischinger said in the closing remarks, "but now I am not fully sure we can do that."

During the three-day event, an array of global security issues, such as conflicts in the Middle East, nuclear issue of Korean Peninsula, trans-atlantic relations, European Union's efforts for deeper defense cooperation, were discussed.

Wonderful visions, ideas, resolutions and initiatives were shared, such as China's One Belt One Road Initiative and a new security treaty between the European Union and Britain after Brexit.

Ischinger continued, after this year's conference, we have known "what the new challenges are, ...what we want to avoid," but concrete steps to implement all the visions and ideas should be done after the conference.

"There is a lot more work ahead," said Ischinger.

Founded in 1963, the annual MSC has become a forum dedicated to promoting peaceful conflict resolution and international cooperation and dialogue.

The 55th MSC will be held on Feb. 15-17, 2019.