Complex sentence: On 12 May, Natalia Poklonskaya was added to the European Union sanctions list, barring her from entering EU countries; and any of her assets there, if existent, are to be frozen.
Split into simpler sentences: On 12 May, Natalia Poklonskaya was added to the European Union sanctions list. She is barred from entering EU countries and any of her assets there, if existent, are to be frozen.