Yes, they would oppose, but they won't do sh!t. US and Mossad knew Pakistan was making nukes, they put Pakistan under sanctions but didn't have the balls to physically stop it. Israeli Air force even came to attack the nuclear reactors like they did in Iraq but they couldn't do anything.
Same with Iran. Iran is under sanctions, but US won't do **** to physically stop you from making them.
Turkey has a greater leverage on the west than both Iran and Pak. Plus they're NATO members. If Turkey wants it, they will get it.