North Korean leader Kim Jong Un turned 40 on Monday with no announced public celebrations at home, after he entered the new year with artillery barrages into the sea and vows to expand his nuclear arsenal.

Since taking power in late 2011, Kim, the third generation of his family to rule North Korea, is believed to have established an absolute leadership similar to his predecessors. But his birthday has yet to be officially celebrated, unlike his late father Kim Jong Il and grandfather Kim Il Sung. Their birthdays are two of the North's biggest holidays and are marked with great fanfare, loyalty campaigns and sometimes massive military parades.