Iran continues its nuclear development unabated, and eventually Israel feels the need to run airstrikes against what is still, at that time, civilian nuclear facilities. The sudden, quick airstrikes prompts many of Israel's neighbors to forget their more immediate differences and form a security pact against further Israeli aggression. The Persian Gulf states stay out of it due to economic interdpendence issues, but Iran, Syria, Egypt, Libya, Lebanon, Jordan, Iraq, and Pakistan organize to that effect.
This security pact is met with condemnation by most of the UN Security Council, including Russia (who has a vested interest against radical Islam). China, however, resolves to work with these belligerents in order to secure favorable energy rights. The UN as a whole by this time has lost patience with the members of the UN Security Council and the way they clearly take advantage of their power to manipulate their interests. America, Britain, and France take advantage of this strong backlash against China's manipulations to pass a resolution to get China thrown out of the Security Council. China leaves the UN entirely in protest.
Alienated from international systems, China solidifies its relationship with that original security pact, and calls for all nations that have been "victimized" by the UN in the past, and other rogues like North Korea, Vietnam, Laos, Myanmar, Serbia, Cuba, Sudan, and Venezuela join this alliance of the ostracized. Eventually Iran feels emboldened by the situation enough to try and oust American and NATO troops from Afghanistan by force. The situation devolves from there.
Granted, the leap in logic in my scenario comes from when China resolves to abandon global systems, rather than just patch things up. It would be a mostly conventional war due to a renewed policy of mutual assured destruction, and the clear imbalance of Nukes in favor of the one side of the conflict (with the only "enemy" nuclear states being China, Pakistan, North Korea, and Iran, who are heavily outweighed by India, Israel, America, Britain, France, and Russia, all on the other side).
Monster Hunter: pissing me off since 2010.
