By Benjamin Harvey, Bloomberg News–

Iran is responsible for security in the Persian Gulf and is taking a stronger stance to protect it, Foreign Minister Javad Zarif said on Monday.

“We used to overlook some violations but we’re no longer overlooking” them, Zarif said at a press conference at the Foreign Ministry in Tehran.

The remarks come after Iran seized a small oil tanker in the Gulf on July 31, saying it was suspected of smuggling fuel. That’s the third ship seized by Iran’s Revolutionary Guards, the nation’s influential elite military unit, since July 14, compounding concerns about the safety of shipping in a region crucial to oil transportation. Iran’s state-run Press TV reported that the latest ship was an Iraqi tanker.

The escalation from Iran’s side came after U.K. forces seized an Iranian tanker on July 4 near Gibraltar. Iran grabbed a British tanker, the Stena Impero, in the Strait of Hormuz two weeks later and continues to hold it.

In seizing the Iranian tanker, the U.K. showed it was “complicit in U.S. economic terrorism,” Zarif said.

To contact the reporter on this story: Benjamin Harvey in Istanbul at bharvey11@bloomberg.net

To contact the editor responsible for this story: Benjamin Harvey at bharvey11@bloomberg.net

For more articles like this, please visit us at bloomberg.com