Five reasons why arms control is a dubious cause.

1.  The project supposes structures that aren't really there.  The world is not a nation state.  A nation can effectively prevent citizens from possessing machine guns - sometimes at least.   That might be a good thing.   But the world cannot prevent all nations from possessing horrible weapons of one sort of another.   The most that can happen is that some nations prevent other nations from possessing certain types of arms.   That's a dubious achievement.  It often creates a strategic imbalance.  There's no evidence that, in general, strategic imbalances  are a good thing.

2.  There is great effort expended to prevent "non-state actors" from possessing certain weapons, particularly 'advanced' weapons.  However at times it is morally imperative that non-state actors possess such weapons, because they are engaged in desperate defensive struggles against monstrous governments.  This was the case in Syria, where arms control aficionados triumphantly uncovered rebel arms channels and gloated over every unveiled MANPADS.  It is unclear whether their efforts actually did substantial harm.  That hardly makes their 'achievement' more defensible.

3.  Arms control campaigners make much of their success in 'banning' cluster munitions and mines.  Mines and cluster munitions are objectionable weapons in a very particular sense:  they lie around for decades and kill or maim innocents long after a conflict is over.  Clearing efforts have rightly  attracted admiring attention.  But these efforts have nothing to do with arms control.  As for the bans,  they are of very dubious value given the virtual impossibility of enforcement and the failure of major nations to ratify the treaty.  Non-signatories who produce cluster munitions include Brazil, China, Egypt, Greece, South Korea, Pakistan, Poland, Romania, and Turkey, India, Iran, North Korea, Singapore, Israel, Russia, and the US.  This doesn't even include non-signatories who stockpile but, they say, have never used the weapons:  Estonia, Finland, United Arab Emirates, Algeria, Argentina, Bahrain, Belarus, Cuba, Jordan, Kazakhstan, Kuwait, Mongolia, Oman, Qatar, Turkmenistan, and Uzbekistan.  Those who insist that cluster munitions are "internationally outlawed" apparently have difficulties with the meanings of "internationally" and "outlawed".  The record on land mines is comparable.

4.  The focus on certain impressively nasty weapons is myopic.  Denied one means, cruel adversaries will find another.  Even if the ban were effective, nations and non-state actors would move to comparably awful devices:  in Syria, the régime uses barrel bombs, far too crude ever to eliminate.  Lacking land mines, the Islamic State has started manufacturing IEDs on an industrial scale.    Nation-states will always possess atrocious weaponry and they will invariably develop new horrors if the old ones are no longer considered acceptable.  Non-state actors do not need fancy weapons and will always have no trouble obtaining the basic tools of their trade, assault rifles, machine guns, mortars, rockets and other cheap, multi-purpose, easily portable devices.  Indeed some of the most awful atrocities in recent memory have been perpetrated with fire, chlorine gas, knives, machetes and clubs.  The idea that you are going to make the world a better place by tracking who has which MANPADS or who is developing what advanced missiles or who is shipping tanks to whom...  that's a non-starter.

5.  Arms control fanatics don't get that their verbal even-handedness doesn't undo the biased tilt of their efforts.  They often condemn, evenhandedly, arms proliferation of any sort, anywhere, whether in the developed world or in the conflict zones of Africa and the Middle East.   But there is not the slightest, tiniest chance that arms control efforts will blunt the impressive capacity of advanced nations to maim and kill innocent civilians, usually from safe distances - when drones are involved, with utter impunity.  The victims are consigned to irrelevance as 'collateral damage', with no prospect that the 'international community' will punish the perpetrators.  The only possible net effect of arms control measures is to increase the already enormous military dominance of great powers over small ones.  Arms control ideology rests on the tacit premise that this must be desirable.

One thing is certain:  making the dominant military powers even more dominant has so far done no good.  To the minimal extent that arms control has affected, for example, the Syrian régime, it hasn't cramped its reign of terror.  Indeed not a single monstrous ruler has ever come close to curtailing his atrocities because arms control "wonks" get nerdy about his supply chain.  Tyrants can always find the means to torture and kill.  Arms control efforts, if successful, do consistently deprive non-state actors of the means to resist their state opponents.  Sometimes this is desirable, sometimes an outrage.  It is dogma, not morality, to deny this.