LTBT
Prohibits nuclear weapon test explosions and any other nuclear explosions in three environments: in the atmosphere, in outer space and underwater, but does not prohibit underground nuclear explosions
underground
underground
underground
Nuclear testing above ground was eventually banned due to the environmental and health risks it posed, such as radioactive fallout and damage to ecosystems. The testing also raised concerns about escalating the arms race and increasing the threat of nuclear war. This led to international agreements, such as the Partial Nuclear Test Ban Treaty, to halt above-ground nuclear testing.
LTBT
The Limited Test Ban Treaty forbids nuclear testing in all areas except underground. Nuclear testing in the atmosphere, under water, and in outer space are all banned.
It banned nuclear testing above ground. 116 countries signed the treaty.
August 5th, 1963 Three of the four nuclear powers sign a limited treaty that bans most, but not all, nuclear weapons testing. The 1963 treaty only banned "Atmospheric" tests (in the air, space, and underwater) not "most". Testing just moved underground and continued at about the same pace, maybe even faster for a while.
They learned about how far fallout can travel and affect people outside blast zones.
Short answer: no. One of the treaties in the 1960's banned above ground testing and all countries (the US, Soviet Union, France, and China) have followed that ban. The US and the Soviet Union agreed, in a separate treaty, to stop underground testing in the 1970's and both have followed that treaty. Other countries, India and Pakistan and possibly North Korea, did not agree to ban all testing and have conducted underground nuclear testing in the last ten years.