Foreign ministers from 12 nations began consultations Saturday on further nuclear disarmament as they met in the Japanese city of Hiroshima, the site of the world's first military use of nuclear weapons in 1945, according to dpa. Their discussions centred on how the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) can be more sharply applied, and the ministers expressed concern over developments in Ukraine, saying that all current international guarantees for its territorial integrity must be upheld. Of particular importance, the group said, was the Budapest Treaty of 1994, by which then-nuclear power Ukraine committed itself to relinquish possession of nuclear weapons in exchange for international promises, including from Russia. With the annexation of Crimea, Russia has breached its commitments under the treaty, the group said. The ministers taking part in the Non-Proliferation and Disarmament Initiative (NPDI) opened the meeting with a memorial to the victims of the US bombing 69 years ago. The memorial included the laying of bouquets at the central memorial in Peace Park in Hiroshima. More than 70,000 people were killed in the initial blast, and it is estimated that 280,000 died from the effects of the bombing in total. "Japan will lead international efforts based on an awareness of the humanitarian consequences of nuclear weapons use and a calm awareness of the diversification of nuclear arms-related risks we are faced with," Japanese Foreign Minister Fumio Kishida said, according to the Kyodo News agency. German Foreign Minister Frank-Walter Steinmeier said that "a world without nuclear weapons is more than just a vision, it is a necessity." The ministers are also discussing the next NPT review conference to take place in 2015. More than 180 countries have signed the treaty since it went into effect in 1970. The countries that sent representatives to Saturday's meeting include Australia, Canada, Chile, Germany, Japan, Mexico, the Netherlands, Nigeria, the Philippines, Poland, Turkey and the United Arab Emirates.