Yemen , officially known as the Republic of Yemen, is a country at the southern end of the Arabian Peninsula. Yemen is the second-largest Arab sovereign state in the peninsula, occupying 527,970 square kilometres. The coastline stretches for about 2,000 kilometres. It is bordered by Saudi Arabia to the north, the Red Sea to the west, the Gulf of Aden and Guardafui Channel to the south, and the Arabian Sea and Oman to the east. Although Yemen's constitutionally stated capital is the city of Sana'a, the city has been under Houthi rebel control since February 2015. Yemen's territory includes more than 200 islands; the largest of these is Socotra.