UNITED NATIONS, Sept. 26 (Xinhua) -- UN Secretary-General Antonio Guterres said on Tuesday that the vision of a world free of nuclear weapons requires a global response.

Addressing a high-level General Assembly meeting held in commemoration of the International Day for the Total Elimination of Nuclear Weapons, observed annually on Sept. 26, Guterres said that the only world that is safe from the use of nuclear weapons "is a world that is completely free of them."

Although the goal of such a world is universally held, he said, it has lately been subject to numerous challenges, including a series of provocative nuclear and missile tests conducted by the Democratic People's Republic of Korea.

He said that the states possessing nuclear weapons have a special responsibility to lead by "taking concrete steps," including those agreed at various review conferences of the Treaty on the Non-Proliferation of Nuclear Weapons (NPT).

Expensive campaigns to modernize nuclear weapons, combined with the absence of planned arsenal reductions beyond the new Strategic Arms Reduction Treaty (START) between Russia and the United States, make it difficult to see how disarmament can make progress, Guterres said, warning against misguided assertions that prevailing security conditions do not permit disarmament initiatives.

"It is true that we live in challenging circumstances, but this can be no excuse for walking away from our shared responsibility to seek a more peaceful international society," he said.

The General Assembly declared Sept. 26 as the International Day devoted to furthering the objective of the total elimination of nuclear weapons through a resolution adopted in December 2013.

Also addressing the event was this year's General Assembly President Miroslav Lajcak, who noted that thousands of nuclear warheads still exist and they are being "stored across three different continents."

More than half of the world's population lives in countries which have nuclear capabilities, or are members of nuclear alliances, he added.

Since the designating the International Day, the world has witnessed three nuclear tests.

"One nuclear test is one too many. Six nuclear tests in the 21st century is, frankly, alarming. So too is the reckless rhetoric we are witnessing. It can bring us all to the verge of a cliff, which we cannot afford to fall off," he said.

"We can live in a nuclear-free world, as long as we all believe that it is possible. And as long as we are all willing to work to make it possible," he said.