New Delhi, Jan. 16 -- Some personnel at a key U.S. military base in Qatar were advised to evacuate by Wednesday evening, according to a U.S. official and the Gulf country, as President Donald Trump has warned of possible action after a deadly crackdown on protesters in Iran.

The decision came as a senior official in Tehran brought up the country's retaliatory attack in June at Al Udeid Air Base outside Doha, Qatar.

The U.S. official, who spoke on the condition of anonymity to discuss sensitive plans, described the move at the base as precautionary and said such measures also were being taken across the region. The official, citing the need for operational security, would not go into further detail, including whether the evacuation was o...