The concern was that in the 1960s the U.S. had the most nuclear weapons stockpiled, which has since declined. But officials in the room reportedly told Trump that although the arsenal is smaller now than it was in the 60s, it is stronger.
Strong, marginal, and weak: The Heritage Foundation's 2017 Index of U.S. Military Strength scores the current U.S. nuclear stockpile as "strong," the second-highest ranking just after "very strong" on their scale. Delivery platforms were also ranked "strong." However, Heritage labeled overall nuclear power "marginal," the third-strongest rank. The "weak" ranking fell to warhead modernization efforts in the U.S. as well as to the facilities that develop and host these components.
No guarantees, pitfalls remain: The nuclear arsenal, like much of the military, suffers from "force degradation resulting from many years of underinvestment, poor execution of modernization programs, and the negative effects of budget sequestration (cuts in funding) on readiness and capacity," Heritage writes. Similarly, future pitfalls to the nuclear stockpile's viability remain since it's not a guarantee that the long-term effects of aging materials won't compromise nuclear weapons. Plus, without nuclear testing, assessments of viability are, in effect, incomplete — simulations these days are based on tests conducted in the 50s and 60s — so problems in the stockpile as it ages may go unchecked.
Put it in perspective: If, indeed Trump wanted to increase the nuclear stockpile, which stands at about 4,000 nuclear warheads right now, that would make the U.S. nuclear muscle greater than all other countries' known nuclear arsenals combined. Trump later Wednesday said it was "frankly disgusting" that media can write whatever it wants. The Pentagon is currently conducting its Nuclear Posture Review.
India, Israel, and Pakistan have not signed onto the Nuclear Nonproliferation Treaty, but are known to have nuclear weapons, according to the Arms Control Association.