MOSCOW, April 28 (Reuters) - Russia's foreign ministry on Friday criticised a nuclear agreement between the United States and South Korea, saying it would destabilise the region and the wider world, and warned of a potential arms race as a result. Washington has accused Moscow of nuclear sabre-rattling over various statements from Russian officials, including President Vladimir Putin, since the start of the Ukraine war that Russia would be prepared to use nuclear weapons to defend its "territorial integrity". See here for a complete list of exchanges and delays