(ANSA) - BELGRADE, MAY 13 - Strengthening NATO's eastern flank, increasing defence spending, and consolidating support for Ukraine. These are the central themes of the Atlantic Alliance's Bucharest 9 (B9) format summit, which is currently taking place in Romania's capital amid the ongoing conflict in Ukraine and tensions with Russia. Voldymyr Zelensky, the Ukrainian president, is also in attendance. Following Russia's annexation of Crimea in 2015, Romania and Poland established the B9 format, which brings together Eastern European NATO countries including Bulgaria, Hungary, Slovakia, the Czech Republic, and the three Baltic states (Estonia, Latvia, and Lithuania). In recent years, the group has emerged as one of the primary instruments of political and military coordination on the Alliance's eastern front. Romanian President Nicusor Dan and Polish President Karol Nawrocki opened the summit, emphasising the importance of strengthening the Alliance's deterrent capabilities. (ANSA).