The U.S. Navy’s Mideast-based 5th Fleet says Iran’s paramilitary Revolutionary Guard seized and later let go of a U.S. sea drone in the Persian Gulf.

Cmdr. Timothy Hawkins, a 5th Fleet spokesman, said Tuesday the incident saw a Revolutionary Guard ship try to seize a Saildrone Explorer.

Hawkins said the Guard vessel was towing the drone behind it as a U.S. Navy ship and helicopter approached it.

Hawkins told The Associated Press the Navy called repeatedly to the Iranians, who ultimately let the drone go.

Iran did not immediately acknowledge the incident. However, it comes amid heightened tensions between Washington and Iran over Tehran’s tattered nuclear deal with world powers.