All countries that have exploded nuclear devices have exploded their first devices.
The USA was the first to detonate such a device and the only country to use nuclear warheads in combat.
The most recent countries to test nuclear devices are India, Pakistan, and North Korea.
Many, but the US Buster-Jangle Uncle effects test was the first. It was 1.2KTons exploded at a depth of about 3 feet, to test cratering effects. It produced massive fallout levels. Most underground testing is done much deeper to prevent contamination.
Both the first fission bomb (the Gadget device exploded in Trinity test July 16, 1945 on a 100 foot tall steel tower in the Jornada del Muerto valley in what is now White Sands Missile Range) and the first fusion bomb (the Sausage device exploded in Ivy Mike test November 1, 1952 on the surface at Enewetak Atoll) were designed and made at Los Alamos in New Mexico.
The US was the first to start testing nuclear weapons
canada
because we were the first country to have them
U.s
every country that has done underground nuclear testing at some point exploded their first underground nuclear device. if you want the first country, that was the US. if you want the most recent, that was North Korea. but this could change any day.
India
US
Many, but the US Buster-Jangle Uncle effects test was the first. It was 1.2KTons exploded at a depth of about 3 feet, to test cratering effects. It produced massive fallout levels. Most underground testing is done much deeper to prevent contamination.
North Korea
1949
India's first nuclear test on May 18, 1974, described by the Indian government as a "peaceful nuclear explosion." The first Nuclear Test in India was cnducted on 18 May , 1974 at Pokhran.
1964
China's first nuclear test took place in 1964 and first hydrogen bomb test occurred in 1967.
shot grable may 25, 1953
The United States of America was the country that developed the first nuclear weapons.