This is not true, but it can be understood for most Westerners to think this is the first time that a nuclear power has been invaded. But it is not.

Pakistan and India, both nuclear powers, have had numerous cross-border invasions and occupations over the years. The most recent of which was the Kargil War in 1999. This was after both countries had been openly declared nuclear powers. Pakistani soldiers and militants infiltrated and occupied the Kargil district of Jammu and Kashmir. This was not a raid. India responded with military force to reclaim the occupied territory, and Pakistan eventually withdrew after much international pressure.