The U.S. is poised to approve sending a Patriot missile battery to Ukraine, finally agreeing to an urgent request from Ukrainian leaders desperate for more robust weapons to shoot down incoming Russian attacks, U.S. officials said Tuesday.

The approval is likely to come later this week and could be announced as early as Thursday, said three officials, who spoke on condition of anonymity because the decision is not final and has not been made public.

Ukrainian President Volodymyr Zelenskyy pressed Western leaders as recently as Monday to provide more advanced weapons to help his country in its war with Russia. Providing Patriot surface-to-air missiles would advance the kinds of defense systems the West is sending to help Ukraine repel Russian aerial attacks, and could mark an escalation.