The access to highly enriched uranium or separated plutonium is the limiting factor for construction of nuclear weapons.

It really depends on how small and how efficient you need to make weapon, a nuclear weapon fitting inside a rocket nose cone is much more sophisticated than nuclear weapon that has to be only transportable by truck, ship or airplane.

For example, the simple design of Little Boy used on Hiroshima contained 64 kilograms of uranium, but less than a kilogram underwent nuclear fission.

https://en.wikipedia.org/wiki/Little_boy

"Unlike the implosion design developed for the Trinity test and the Fat Man bomb design that was used against Nagasaki, which required sophisticated coordination of shaped explosive charges, the simpler but inefficient gun-type design was considered almost certain to work, and was never tested prior to its use at Hiroshima."

So with access to highly enriched uranium (enrichment greater than 90%), a large and crude bomb could be produced in few weeks. How could they deliver it anywhere? They don't have airplanes. Truck? Speedboat?