The question implies that Pakistanis are brain damaged children. They built it on their own and don't let the US or anybody else know the details. The Soviets and the French had similar proprietary feelings about their nukes. Like the US also has. Could a dangerous situation arise? You Betcha. But nobody as close to India as the US is or as close to Israel as the US is will have much success in finding out the Pakistani secrets.
Report: IDF find M-16 rifle hidden in Palestinian's car in West Bank (Haaretz)
from the article: With all eyes on Iran, who's watching Pakistan's nuclear arsenal?