WASHINGTON (AP) — Four Iranian small boats harassed a U.S. Navy warship near the Persian Gulf, but no missiles were fired, the chief of naval operations said Wednesday. 
 
 Adm. John Richardson said the incident involving the guided missile destroyer USS Nitze reflects the greater competition the U.S. is facing at sea. He added it underscores the naval tensions with Tehran, which include other similar incidents as well as the brief detention in January of 10 U.S. Navy sailors who mistakenly steered into Iranian waters. 
 
 A U.S. defense official said the Iranian boats approached the Nitze at high speed on Wednesday, in an unsafe and unprofessional manner. The destroyer fired ten flares in the direction of the Iranian boats and sounded the ship's whistle several times in an effort to warn the boats away, the official said. The Nitze also tried to communicate with the Iranians over the radio, and also changed course to avoid the vessels. 
 
 The official said two boats ignored the warnings and continued to speed toward the Nitze until they were within 300 yards of the U.S. ship. 
 
 The USS Nitze was in international waters in the Strait of Hormuz with the USS Mason, also a guided missile destroyer. The official wasn't authorized to discuss the incident publicly so spoke anonymously. 
 
 Richardson said the encounter raises questions about what is the "new normal," adding, "We have to be mindful that we don't become complacent as things get steadily busier, steadily more engaging and that we're thoughtful about how we approach those challenges." 
 
 Last December, Iranian ships fired rockets near U.S. warship and other vessels in the Strait of Hormuz, and a month later flew an unarmed drone over the USS Harry S. Truman aircraft carrier in the Persian Gulf. 
 
 The January detention incident triggered a Navy investigation which found that the sailors failed to navigate properly and did not use appropriate communications as they sailed near Farsi Island, a base for the Iran Revolutionary Guard Corps Navy in the Persian Gulf. 
 
 The Iranians boarded the boats, pointed their guns at the U.S. sailors and took them to the island where they were held overnight. They were released after Washington intervened. 
 
 Several of the sailors were fired from their jobs or disciplined in connection with the incident. 

 WASHINGTON (Reuters) - Four of Iran’s Islamic Revolutionary Guard Corps (IRGC) vessels “harassed” a U.S. warship on Tuesday near the Strait of Hormuz, a U.S. defense official said, amid Washington’s concerns about Iran’s posture in the Gulf and in the Syrian civil war. 
 
 The official, speaking on the condition of anonymity, said on Wednesday that two of the Iranian vessels came within 300 yards of the USS Nitze in an incident that was “unsafe and unprofessional.” 
 
 The vessels harassed the destroyer by “conducting a high speed intercept and closing within a short distance of Nitze, despite repeated warnings,” the official said. 
 
 IRGC, the Islamic Republic’s praetorian guard, is suspicious of U.S. military activity near Iran’s borders and appears to be sticking to a familiar posture in the Gulf that predates last year’s nuclear accord between Iran and six world powers, including the United States. 
 
 The United States and other countries are concerned about Iran’s support for Syrian President Bashar al-Assad, its ballistic missile program, and its backing for Shiite militias that have abused civilians in Iraq. 
 
 The U.S. defense official said that in Tuesday’s incident the USS Nitze tried to communicate with the Iranian vessels 12 times, but received no response. It also fired 10 flares in the direction of two of the Iranian vessels. 
 
 “The Iranian high rate of closure... created a dangerous, harassing situation that could have led to further escalation, including additional defensive measures by Nitze,” the official said. 
 
 USS Nitze had to change course in order to distance itself from the Iranian vessels, the official said, adding that the incident could have led to a diplomatic protest, but the United States does not have diplomatic relations with Iran. 
 
 It remains to be seen whether these actions were carried out by rogue Revolutionary Guard commanders or sanctioned by senior officials in Tehran, said Karim Sadjadpour, an Iran expert at the Carnegie Endowment for International Peace. 
 
 “For four decades the Revolutionary Guard have been told that America is the greatest threat to the Islamic Revolution,” said Sadjadpour. “This institutional culture hasn’t changed after the nuclear deal,” he added. 
 
 Footage taken aboard the USS Nitze of Islamic Revolutionary Guard vessels. via REUTERS TV 
 
 In January, 10 U.S. sailors aboard two patrol craft were detained by the IRGC when they inadvertently entered Iranian territorial waters. They were released the next day after being held for about 15 hours. 
 
 The Gulf separates Iran from its regional rival Saudi Arabia and a U.S. naval base in Bahrain.
– Four Iranian boats “harassed” a US Navy warship near the Persian Gulf, ignoring orders to back off, Reuters reports. A defense official said two of the Iranian Revolutionary Guard vessels came within 300 yards of the guided missile destroyer USS Nitze on Wednesday at a high rate of speed—an "unsafe and unprofessional” move, per the official. The Nitze made 12 efforts to contact the Iranian boats, got no reply, and fired 10 flares at them. The Nitze changed course to avoid the vessels, the AP reports. "The Iranian high rate of closure... created a dangerous, harassing situation that could have led to further escalation, including additional defensive measures by Nitze," the official said. "For four decades the Revolutionary Guard have been told that America is the greatest threat to the Islamic Revolution," an Iran expert at the Carnegie Endowment for International Peace tells Reuters. The incident in the Strait of Hormuz follows several other tense encounters between the two countries in recent months near Iran’s territorial waters. Adm. John Richardson, chief of naval operations, confirmed the incident, telling the AP it is time to question what is the “new normal” in relations with Iran. "We have to be mindful that we don't become complacent as things get steadily busier, steadily more engaging and that we're thoughtful about how we approach those challenges,” he said. In January, Iran detained 10 US Navy sailors who strayed into Iranian waters. The same month, Iran flew an unarmed drone over the USS Harry S. Truman aircraft carrier. In December, Revolutionary Guard vessels fired rockets near a US warship in the Strait of Hormuz.