Guatemala has ratified the United Nations-backed international treaty banning nuclear tests, bringing the number of State parties to 156.

Out of a total listed number of 195 States, 182 have so far signed the Comprehensive Nuclear-Test-Ban Treaty (CTBT).

For the treaty to enter into force ratification is required from the so-called Annex 2 States. Of these China, the Democratic People’s Republic of Korea (DPRK), Egypt, India, Iran, Israel, Pakistan, and the United States have yet to ratify it. The Indonesian parliament took the decision to ratify the treaty on 6 December 2011.

Guatemala’s Foreign Minister, Haroldo Rodas Melgar, handed over the instrument of his country’s ratification at a ceremony yesterday at UN Headquarters in New York.

Welcoming this move, Tibor Tóth, the Executive Secretary of the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), said Guatemala’s ratification is an important building block towards a world free of nuclear weapons.

“It underlines Guatemala’s commitment to outlaw nuclear testing and to enhance non-proliferation and disarmament worldwide,” he stated.

Latin America and the Caribbean was the first region in the world to establish a nuclear-weapon-free zone with the Treaty of Tlatelolco in 1967.

“Guatemala’s ratification of the CTBT is a boost for the Treaty of Tlatelolco, which will soon celebrate 10 years of being the world’s first nuclear-weapon-free zone to include all countries in the region,” noted Mr. Tóth. “This bodes well for the CTBT.”

Among the 33 States in the Latin America and the Caribbean region, 31 have now ratified the CTBT, with Cuba and Dominica being the only countries that have not yet signed or ratified.

UN is urging all remaining nations to sign and ratify the CTBT, with the aim of bringing it into force by 2012.

The years following World War II saw rapid development of nuclear weapons, first by the United States, and then, with about a five year delay, by the Soviet Union. Testing of these A-bombs and H-bombs in the atmosphere produced "fallout", that is, radioactive elements dispersed through the upper atmosphere, settling down later at points far from the test site. In widespread protests, citizens expressed concern at the presence of radioactive elements such as strontium-90 (9038Sr). This isotope, with a 30-year half-life, is chemically similar to calcium, and so was incorporated at increased levels in dairy products at the market.

Although President Eisenhower, in the 1950s, initially favored an international ban on all nuclear testing, many in the U.S. believed that the Soviets could not be trusted. Above ground tests could be monitored, since a nuclear explosion would produce detectable radioactivity in the atmosphere, but the Soviets could cheat by testing in underground caverns.