BUCHAREST (Reuters) - Two American F-35 fighter jets landed at a Romanian air base on Thursday, Bucharest's defence ministry said.

       The jets, belonging to U.S. Air Forces in Europe will train and run missions with the Romanian military in the coming period.

       On Thursday, NATO ordered its military commanders to intensify preparations to defend allied territory after Russia invaded Ukraine, putting hundreds of warplanes and ships on alert and agreeing to increase troop numbers on its eastern flank.

       (Reporting by Luiza Ilie)