A former nuclear launch officer has let loose a stinging volley of tweets at Donald Trump after reports that the Republican presidential candidate asked a foreign policy expert why the U.S. can't launch nuclear weapons.

John Noonan, who once had a finger on one of the crucial buttons for the 90th Missile Wing at the F.E. Warren Air Force Base in Wyoming, unleashed 20 devastating messages on Twitter Wednesday.

They came as a reponse to the report from MSNBC's Joe Scarborough - citing an unnamed source - that Trump repeatedly asked why the U.S. can't use nukes.

"Several months ago, a foreign policy expert on the international level went to advise Donald Trump," Scarborough said. "And three times [Trump] asked about the use of nuclear weapons. Three times he asked at one point if we had them why can't we use them."

this man held one of the two keys necessary to turn to launch an ICBM. Read his tweetstorm here. You must. https://t.co/0BYknnGxLz — John Podhoretz (@jpodhoretz) August 3, 2016

Noonan, who is also a writer for the Weekly Standard, said in the tweets that Trump would be "undoing six decades of proven deterrence theory" and making "the single greatest strategic shift in U.S. national security in decades."

"What really concerns me," he continued, "is the idea of a narcissist walking around with nuclear authenticators.

"Imagine having to turn launch keys not knowing if we were under attack or if it was because [a] foreign leader said a mean thing on Twitter. The power is there to kill millions. Permanently alter the geopolitical landscape. It is a sacred, sobering responsibility."

Noonan pulled no punches in the 20-tweet rant, also declaring: "Nuclear deterrence is about balance. Trump is an elephant jumping up and down on one side of the scale."

Here's his full, worrying, assessment.

1. I cant get this in one tweet. So bear with me as I air some laundry here on Scarborough's claim Trump's interested in nuclear First Use — John Noonan (@noonanjo) August 3, 2016

2. Pulled 300 nuclear alerts, 100 ft under the Wyoming turf. Job is serious and full of serious people. — John Noonan (@noonanjo) August 3, 2016

3. When we went into ICBM training, we went through a battery of tests and interviews. Are you sane? Are you willing to turn your key? — John Noonan (@noonanjo) August 3, 2016

4. I see how those might sound at odds. — John Noonan (@noonanjo) August 3, 2016

5. But the whole idea behind nuclear deterrence is that you don't use the damn things. So I thought the mission credible and worthy. — John Noonan (@noonanjo) August 3, 2016

6. There are a hell of a lot of bad actors out there who have nukes. They are restrained only by our ability to instantly lay waste to them. — John Noonan (@noonanjo) August 3, 2016

7. The nuke triad, which Trump doesn't have a clue about, has been the single greatest contributor to global peace for decades. You heard me — John Noonan (@noonanjo) August 3, 2016

8. I dont know if Scarborough is telling whole truth here. Anonymous sources suck. BUT... if he is... buckle the hell up. — John Noonan (@noonanjo) August 3, 2016

9. Because Trump would be undoing 6 decades of proven deterrence theory. The purpose of nukes is that they are never used. Trump disagrees? — John Noonan (@noonanjo) August 3, 2016

10. This would be the single greatest strategic shift in US national security in decades. In a Trump Presidency, our foreign policy — John Noonan (@noonanjo) August 3, 2016

11. ....would be this. "Leave our alliances, fall back on a nuclear first use policy." Does he understand just how F'ing dangerous that is? — John Noonan (@noonanjo) August 3, 2016

12. But what really concerns me, as a former nuke guy, is the idea of a narcissist walking around with nuclear authenticators. — John Noonan (@noonanjo) August 3, 2016

13. I could sit 100ft underground, on alert, knowing that the POTUS would not make me do my duty — not unless it was absolute last resort — John Noonan (@noonanjo) August 3, 2016

14. But imagine having to turn launch keys not knowing if we were under attack or if it was b/c foreign leader said a mean thing on twitter — John Noonan (@noonanjo) August 3, 2016

15. The power is there to kill millions. Permanently alter the geopolitical landscape. It is a sacred, sobering responsibility. — John Noonan (@noonanjo) August 3, 2016

16. Idea that nukes would be used, say over Raqqa or Mosul, simply because we have no more allies and it's a simple, easy fix is nauseating — John Noonan (@noonanjo) August 3, 2016

17. Simply signaling that you're open to using strategic weapons as a tactical solution rewrites the rule book. Russia, China, others will — John Noonan (@noonanjo) August 3, 2016

18. respond. Nuclear deterrence is about balance. Trump is an elephant jumping up and down on one side of the scale. So damn dangerous. — John Noonan (@noonanjo) August 3, 2016

19. But geopolitics aside, I can't get my mind off the young officers on nuke alert right now. Wondering if they'll soon answer to a madman. — John Noonan (@noonanjo) August 3, 2016