Warning sirens sounded again early Monday in Bahrain, and at the same time the Islamic Revolutionary Guard Corps said that during its second phase of retaliatory operations it targeted a military base in Sheikh Isa, Bahrain.

The IRGC claimed that repair and maintenance facilities for helicopters, the hangar of a reconnaissance aircraft, and a drone command center of U.S. forces at this base were targeted, and it warned that “retaliatory operations will continue.” The claim has not been independently verified.

For the second consecutive day, Bahrain’s Ministry of Interior asked citizens and residents to take shelter in the nearest safe location and has not published any report of damage so far.

The U.S. Navy’s Fifth Fleet headquarters is based in Bahrain, but not at the Sheikh Isa base; Sheikh Isa is a Bahraini base that has hosted military operations and U.S. aircraft.

These developments occurred after the U.S. Army carried out a new wave of attacks on Islamic Republic targets early Monday.