the USA in 1945
I guess it's Pakistan.
No one. The first nuclear device was not tested until July of 1945, and the first bomb was not produced (not used) until later that month.
1945 was the first year that a Nuclear bomb was successfully tested then used in combat.
The Soviet Union tested their first atomic bomb in 1949.
1949 when the USSR tested their first atomic bomb.
Russia developed its own atomic bomb by conducting extensive research and espionage on the American nuclear program. They successfully tested their first atomic bomb on August 29, 1949, becoming the second country to possess nuclear weapons after the United States.
US
The hydrogen bomb was first tested in 1952 by the United States in a test known as "Ivy Mike." This bomb utilized nuclear fusion to release a significantly more powerful explosion compared to atomic bombs.
The first bomb that was used on people (Little Boy) used Highly Enriched Uranium as its fissile material. The first tested bomb at the Trinity Test used Plutonium as its fissile material.
I think it was Arizona Actually the nuclear bomb called the Manhattan Project was made and tested in New Mexico.
The first Nuclear weapon was created by a team of American Scientist's, known as the Manhattan project. It was first tested and used in 1945, not long before we used them on Japan.
After USSR (mostly in asia), China.