Immediately before and after the collapse of the Soviet Union, Russian and
American leaders worked on a treaty known as START. What was the purpose
of this treaty?

Explanation:

START I (Strategic Arms Reduction Treaty) was a bilateral treaty between the United States of America and the Union of Soviet Socialist Republics (USSR) on the reduction and limitation of strategic offensive arms. The treaty was signed on 31 July 1991 and entered into force on 5 December 1994.

you didn't give any answers to choose from so i can't with this but, i do know something that the mexican government would be worried about and that is the wall that donald trump is currently trying to get up.