Becuase I hate you!
No they did not yet
The U.S. used the pacific atolls because they were isolated from large population centers and because the Marshal Islands (where many of these atolls were) were entirely under U.S. control after WW2, so could freely involuntarily evacuate indigenous populations of the atolls that testing was planned on. The USSR did all of their testing inland for security reasons (they also did not have control over any atolls). The British did much of their testing inland on Australia and some in the pacific on Christmas island. The French did their testing in the Sahara desert. The Chinese did all of their testing inland for security reasons. etc.
Atolls
Atolls are created from coral reefs that grow on the rims of submerged volcanic islands. As the islands erode over time, the coral reefs continue to grow upward to maintain a balance between erosion and coral growth. This process prevents the atolls from sinking.
Kiritimati or Christmas Island
atolls
Atolls are low-lying coral islands that are formed from coral reefs growing around the rim of an ancient volcanic island that has sunk below sea level. They are characterized by a central lagoon surrounded by a ring of coral reef and sandbars.
Atolls are ring-shaped coral reefs, often found in the open ocean and surrounding a lagoon. They form from the growth of coral reefs around a submerged volcanic island that erodes over time, leaving a ring of coral islands. Atolls are typically found in tropical areas with warm, shallow waters.
Tuvalu is made up of nine islands, eight of which are inhabited. Tuvalu, means "eight standing together".
Tokelau consists of three coral atolls, Atafu, Nukunonu, and Fakaofo.
Volcanic islands, coral atolls
coral reefs barrier reefs fringing reedfs atolls