Large-scale Russian military exercises were being held off the southern coast of Ukraine on Monday, with aircraft, helicopters and more than 30 warships gathering in the Black Sea as fears over a possible attack by Moscow grew. Russia says the training is aimed at locating and destroying submarines. Ukraine calls the drills, which are expected to last through Saturday, a provocation that will severely impede navigation in the Black Sea and the adjacent Sea of Azov. The Kremlin has rejected accusations that merchant ships would be impacted by the manoeuvres and said they pose no security threat…