AP Photo/Jacquelyn Martin
- Biden promised retaliation after a drone attack killed 3 US troops in Jordan on Saturday.
- Biden called the attack "despicable."
- The attack marks the first line-of-fire deaths for US troops since the start of the war in Gaza.
A drone attack killed three US service members and injured at least 25 others in Jordan, near the Syria border, on Saturday, according to President Joe Biden.
The deaths are the first US military fatalities connected to the conflict in Gaza, which began last October.