A bit old, but worth noting….this 2018 Treasury report has this to say about Pakistan:

Like China and Russia, Pakistan is a nuclear weapons state but there is no U.S. targeted financial sanctions program dedicated to Pakistan for the development and maintenance of its nuclear weapons program. Unlike China and Russia, however, Pakistan is not a party to the NPT and therefore is not recognized under international law as having the right to the peaceful use of nuclear energy, to include the transfer or acquisition of nuclear technology. As a result, the Pakistani nuclear program has been marked with controversy since its inception, not just in its own right as a state-led program going against the grain of international norms, but also due to the outward proliferation tied to former members of the program in future years. Having to operate outside of regulated international channels has meant that Pakistan has largely had to acquire technology and know-how through covert means, and in select cases, those acting for on behalf of Pakistani government entities have sought to procure U.S.-origin goods and facilitate these illicit transactions by exploiting the U.S. financial system.