Yes and no.
Up into the 1990s I would say that this was entirely true. Throughout the extent of the Cold War, the biggest deterrent against maor powers going to war was MAD (mutualy assured destruction) brought on by nuclear fallout. While that is still a threat today, the biggest deterrent to ar is economic MAD.
Globalism has made our economies so interweaved that they are reliant upon eachother. China relies upon the USas its market and as a place to steal technology form (instead of inventing it itself). The US relies on China largely as its factory and for many raw materials. Western Europe relies on Chinese goods and Russia Oil. Russia relies on China for market share and as an oil customer. Russia relies on Western Europe as a customer for its oil. The US and Europe rely on each other as major markets for export.
Send any of two of the four of the world's major powers and the ENTIRE net could and likely would falling apart, starving many nations of manufcturing ability and others of a place to sell their wares, plunging them into severe economic depression.
So while nuculear weapons still remain a deterrent, they have been surpassed by the new economic deterrent.