Scientists that develop technology and vehicles to deliver the technology are not brothered about the strategic policies of the day's govt. When they test and develop a technology, their motivation is to extract maximum possible positive output from the test and use it in all possible scenarios and intensities. When the scientists tested sub kilo ton devices, they did not expect that we would have a government that declares and adopts a no first use policy. Similarly when they developed a suitable vehicle to deliver such devices, they were just making the nation to be ready with all available means to protect , defend and if needed charge against our enemies. If we continue to have a favorable govt in the US after the next elections, I bet our govt would write off the no first use policy. Even with no first use policy, there are always ways to use these as a full scale retaliation, with localized serious damage to the stupidity of enemies.