I am not sure, a completely dependent world may make us safer as wars will very hard to execute.
China has a near monopoly on a lot of production. Countries that depend on them certainly won't go to war with them, but that doesn't hinder China from starting a war with those countries, and even gives them an advantage. And it doesn't stop dependent countries from warring with each other and that could even be beneficial to China.
N.B. I use China as an example only. Replace China with any country that might have a near monopoly on production of some kind. The point I'm trying to make isn't "ahhh China scary", it's that interconnectedness may only prevent war if it's actually interconnected, and not a monopoly.
I think the "global interdependence reduces war" hypothesis is pretty strong.
And if the seller is a monopoly on a critical good while the buyer is a tiny fraction of their business, the relationship is asymmetrical and the seller won't suffer nearly as much from a war.
But it does open up avenues for conflict less intense than invasion. The term 'weaponized interdependence' has recently been coined for this. An exploration:
http://henryfarrell.net/wp/wp-content/uploads/2018/05/Weapon...
It was more a claim about Western European countries, which, propaganda aside, were not puppet-states of the US.
Cold-war era US puppet-states were different, and at the time mostly didn't tend to have Macdonald's, at least outside of a capitol. We were busy subverting their democracies, and civil unrest doesn't go well with Big Macs.
Interdependence, even to the point that war is utterly ruinous with no upside, is no guarantee war wont happen, don't make the mistake most people in Europe did before WWI
I think it's popular today as a distraction from the fact that the American Empire is really held together by military occupations in Europe, Asia, the Middle East, Latin America etc. and not economic ties. Obviously "we just want to make you rich" is much nicer sounding than "we will bomb you if you resist US hegemony".
A major rising power that feels it is being denied its "rightful place" in the world order by the existing power brokers (Germany vs the UK/ China vs the USA) lead by a hardline leader that isn't interested in compromise (Kaiser Wilhelm II/Xi Jinping)
A series of interlocking mutual defensive pacts that will automatically draw nations into war (The alliance of the UK, France and Russia vs Germany and the Austria-Hungary Empire/NATO vs China and Russia)
Regional fighting that is close to leading to direct confrontation between said power blocks (The Balkans/Turkey and Syria)
Rising Globalism and trade interdependance, along with rising nationalistic rhetoric and jingoism, and intense competition for influence in 3rd party states (The scramble for africa/Africa and south east asia and former CIS states).
The major powers slept walked into a horrible war because the rising tensions made it inevitable, and nobody took heroic steps to stop it, sadly it looks like it might be happening again.
Nobody wanted a ruinous war, and most people thought that there was no way a war could really occur or at the very least be sustained due to the need for trade. (Germany at the start of WWI was critically short on stuff like gasoline, fertilizer and the raw materials for gunpowder)
It Happened anyways.
Don't think for a second it can't happen again.
For NATO, the key part is Article 5 that specifies "armed attack against one or more of them in Europe or North America shall be considered an attack against them all", and is intentionally drafted so as to not apply to "Cold war turning hot" in Asia (e.g. the Korean war or Vietnam war or Afghanistan or Iraq) and to any "non-core territories" e.g. French or British overseas territories or pacific islands like Guam. Heck, a literal repeat of Pearl Harbor and invasion of Hawaii would not trigger Article 5 (though NATO could and would likely take action despite not being required to do so) - the NATO treaty is explicitly designed to not draw nations automatically into war unless USSR or someone else starts WW3 in Europe or attacks mainland USA. It's hard to imagine any Chinese actions regarding their ambitions (e.g. South China Sea, Taiwan, Hong Kong) that could trigger the NATO Article 5 which would automatically draw nations into war, anything in Asia would give each nation a choice whether to get involved and if so, how much.
I'm not informed about the Russia-China treaties much, but IMHO they also don't have any strong mutual defence pacts, they have some limited military cooperation and sharing but that's it; they had a mutual defence pact in 1950s but that's long gone now. For example, there's the https://en.wikipedia.org/wiki/2001_Sino-Russian_Treaty_of_Fr... where the strongest relevant obligation in Article 9 would require each party, if it's attacked, to.... immediately contact the other and consult about the situation; it does not include any agreement or obligation to actually do anything about it.
But "safer" doesn't necessarily mean "no wars." It's rare, but sometimes wars are just (e.g. ones against those who commit crimes against humanity). A world so economically interdependent that war is truly unthinkable is one where even peaceful coercion like sanctions are too costly to pursue. I don't want economics to enslave morality.