We are in an era where it is more difficult for major powers to cooperate on a major international crises. It is obvious that the hegemonic power of the US is undermined, and new power- like China is quickly on the rise. This lack of a hegemonic power is also the reason why states- especially the powerful ones are more aware than ever that a rational behavior can result in costly outcomes.
This kind of action can be seen through the crisis in Ukraine- the bigger powers like China, India, and Brazil were quiet in midst of the crisis, which just proves that politics is not just about power anymore. We are not in an era where a greater power can easily control the smaller states. The states are also aware that positive-sum games are impossible to achieve, Therefore, they are not willing to take any actions that could effect them in any way. Realists would say that positive- sum games was never an option that could have been achieved even in the past. However, it is not until now that countries, increasingly, are governing themselves with a more realistic approach.
So, what is so different with the major power relations today? States are aware that there is no hegemonic power in the world right now. It is not only about money and the power anymore. War is also not only about balancing of the powers. More states need protection, but less states are willing to cooperate, and it is more transparent than ever that states- even the US are more hesitant in providing more protection for the weaker states. This may be because the U.S. is aware that other powers are on the rise. Or, this could also be because U.S. is also in need of security. Whatever the reason may be, cooperation of the states is harder to achieve in the present day, and may become even more difficult. Only time will be able to tell if any states will continue to govern or present their states in a liberalistic manner.