on june 26, 1940 the soviet government issued an ultimatum to the romanian minister in moscow, demanding romania to immediately cede bessarabia and northern bukovina. italy and germany, which needed a stable romania and access to its oil fields urged king carol ii to comply. under duress, with no prospect of aid from france or britain, romania ceded those territories. on june 28, soviet troops crossed the dniester and occupied bessarabia, northern bukovina, and the hertza region. territories where ethnic ukrainians were the largest ethnic group (parts of northern bukovina and parts of hotin, cetatea albă, and izmail), as well as some adjoining regions with a romanian majority, such as the hertza region, were annexed to the ukrainian ssr. the transfer of bessarabia's black sea and danube frontage to ukraine ensured its control by a stable soviet republic.