Mild to moderate ASB incoming with shades of Clive Cussler (note - I don't endorse the behavior of anyone in this scenario):
A Nice Day for a White Wedding
POD: During the Budapest Memorandum talks, Russia and Ukraine agree to create the Eurasian Energy and Defense Community (EEDC), allowing nuclear energy workers from Russia to work in Ukraine and vice versa so long as the two nations were at peace. Nuclear weapons engineers are also allowed to migrate, but can be deported at a moment's notice by either government. In time, Belarus and Kazakhstan join the EEDC; the only criteria are being a state in Eurasia that is not aligned to NATO or another rival power (Sweden, although an EU member, gets more than halfway through talks to join before an election). By 2008, over 1,000 workers from Ukraine are living in Russia, including approximately 150 in the weapons division. Specifically, much of the software behind the Russian nuclear system is written by two Ukrainian engineers and a Russian of Ukrainian origin. Ukrainian-origin software also sneaks into the Chinese and North Korean nuclear weapons system.
Literally as soon as the Euromaidan protests begin, the Ukrainian nuke workers begin to fear that relations will deteriorate between the two countries and will lose their jobs. Specifically, one of the two Ukrainian coders is a Right Sector supporter who hates non-whites as well as Putin, and when the much-feared order for all Ukrainian weapons engineers to leave is given, nobody notices that he has left a backdoor into the system. On the one-year anniversary of Euromaidan, he sends an email to a white nationalist-leaning worker in the Russian nuclear weapons program, codenamed "White Wedding" in a dual Billy Idol/Game of Thrones reference. That worker uploads a computer worm to the North Korean nuclear control system, causing it to slip out of the control of the generals. Tokyo, Yokohama, Osaka, Kyoto, Seoul, Busan, Tianjin, Beijing, Shanghai, Hong Kong, Macau, and Taipei are devastated, as are the capitals of two Asian-majority republics in Russia, Sakha and Tuva, and the important Asian port of Nakhodka. Another nuclear weapon strikes Russia's famed Lake Baikal, irradiating some of the world's most pristine water. In 12 hours, most of the successful non-Western countries have collapsed into chaos: Taiwan, Hong Kong, Macau, Japan, and South Korea; a flood of refugees from China brings Singapore and the Malay peninsula down by the end of the month.
The world by 2017 is an interesting place. China has lost control of Tibet and Xinjiang as it has attempted to put down a far-left faction in Chongqing; although the map shows the Han lands as peaceful that is barely the case. China, South Korea, and a rump North Korean regime are locked in a war for Northeast Asia. The southern half of Honshu is undergoing a very expensive, US-led rebuilding effort and is still under martial law; conditions in the remainder of the country are somewhat better, but not great. Taiwan is independent with a provisional capital in Kaohsiung, although it has been forced to open fire on mainlander boat people. Mainland (and Singaporean) refugees are also flooding into Myanmar, Laos, Vietnam, and Borneo. Russia has gone raving mad after learning that one of the hackers behind White Wedding was Ukrainian, expelling all Ukrainians from the country, although they're putting up a surprising resistance in the Kuban and the Far East. Outraged that the government was focusing so much on rebuilding Yakutsk, Tuva split from the Russian Federation and only now are Russian troops making inroads. The only people really happy are hardcore white supremacists, as most all of the successful non-white societies have collapsed into chaos and war.