Iranian Foreign Minister Mohammad Javad Zarif said Friday that a US-led maritime security mission in the Strait of Hormuz would be a "source of insecurity."
 The United States has been seeking allies for a naval mission to guarantee freedom of navigation in the region after Iran seized two foreign oil tankers in recent weeks in apparent retaliation for Britain impounding an Iranian tanker in early July.
 The rising tensions in the Gulf come as the US, which last year withdrew from a 2015 nuclear deal, imposes sanctions and a so-called "maximum pressure" campaign against Tehran.
Britain has agreed to join the US-led naval mission, but other European nations, including Germany, have been reticent for fear of being dragged into an all-out conflict. European countries have been trying to preserve the 2015 deal, which limited Iran's nuclear activity so as to make it technically impossible for the Islamic Republic to acquire nuclear weapons. But they have been largely unable to counteract the crippling effect of the reimposed US sanctions, which have led European firms too to pull out of Iran.
 "Gulf is vital lifeline and thus nat'l security priority for Iran, which has long ensured maritime security [sic]," Zarif wrote on Twitter on Friday. "Mindful of this reality, any extra-regional presence is by definition source of insecurity - despite propaganda. Iran won't hesitate to safeguard its security," he added.
 Iran impounded a British-flagged and a Panamanian-flagged oil tanker in recent weeks for allegedly breaking international law and smuggling oil, respectively. The moves were widely seen as retaliation for the seizure of an Iranian tanker by US ally Britain off Gibraltar.
 London alleged that that vessel was carrying oil to Syria contrary to EU sanctions. On Sunday Tehran also claimed to have impounded an Iraqi-flagged vessel for oil-smuggling. France meanwhile hit back at a tweet by US President Donald Trump, who on Thursday said his French counterpart Emmanuel Macron was sending "mixed signals" to Tehran and added that nobody was "authorized" to represent the US. France "requires no authorization" to engage diplomatically with Iran, Foreign Minister Jean-Yves Le Drian said in a statement.
"The heightened tensions require political initiatives to restore the conditions for dialogue," Le Drian said. France was "true" to its signature to the 2015 accord "as are the other signatories, apart from the United States," Le Drian said in a statement. Paris "firmly asks Iran to resume compliance with its obligations," he added.
Iran has responded to the US sanctions by gradually breaching some of the limits set by the agreement.