Iran repeated its tactic of harassing American naval vessels in the Persian Gulf on Monday, as three IRGC speedboats came dangerously close to US ships, the Washington Post reported.

The vessels, the USS Sirocco, a patrol ship, and the USS Choctaw County, a fast transport vessel were in routine operations in international waters when three Iranian fast-attack boats came as close as 50 yards at “dangerously high speed.” The encounter lasted for an hour; sources told the Post.

The two US naval vessels issued warnings to the Iranian boats and the Sirocco eventually deployed a warning flare.

Iranian speedboats have harassed US Navy vessels on many occasions in the past but have not been met with direct fire.

Tensions have risen in the region after year-long talks to restore the 2015 nuclear agreement came to a standstill in March and Tehran received a warning for the International Atomic Energy Agency’s board of governors earlier in June for not cooperating with the UN watchdog.

Israel announced on Monday that an air defense coalition is being formed in the region with US leadership and it has already thwarted Iranian attacks.

The Revolutionary Guard navy’s move comes as Iran’s main demand at the nuclear talks is for the US to lift terrorism sanctions imposed on the entity, which is accused of supporting militant groups in the region.