My take is that they'll not only allow it, they'll happily and gleefully sell it to Singapore. Since ICBM and SSN the whole world is under nukeable zone from US and UK nuke missiles, let's not fool ourselves. At any time of the day or night, there's a nuke sub of theirs lurking somewhere within range of anywhere including ours of course. It costs a lot money. A good ally willing to pay and help defray their costs is most welcome to them. But why would we want to help them pay, you may ask. The answer is in my earlier post. We're allies but not blood-brother allies like Canada, Australia and NZ standards. We need the ability to decide when the push the button.