The United States on Friday imposed more sanctions, targeting the Central Bank of Iran, which was already under US sanctions
Trump has said he is considering how to respond and that military action is an option
Minister of State for Foreign Affairs Adel al-Jubeir said the probe would prove that the Sept. 14 strikes had come from the north and that Iran bore responsibility
Iran has denied involvement in the Sept 14 attack in Saudi Arabia that was initially claimed by Yemen's Iranian-backed Houthi rebels
US to deploy forces in Gulf on after drone attacks on Saudi oil facilities
Iran again denied involvement in the Sept. 14 raids, which hit the world's biggest crude oil processing facility and initially knocked out half of Saudi output
US Secretary of Defense Mike Esper also singled out Iran as a regional destabilizing force, while stopping short of directly accusing Tehran over the strike
Yemen's Iran-aligned Houthi group claimed credit for the attacks on two plants at the heart of Saudi Arabia's oil industry
Iran is throwing down a new challenge to European leaders struggling to sustain their diplomatic push to calm the Gulf
Macron has been leading efforts to de-escalate the situation and he expressed hopes of bringing together Rouhani and Trump for a meeting during a G7 summit days ago
State Department spokeswoman Morgan Ortagus said the Grace 1 was assisting Iran's Revolutionary Guards, which the US deems a "terrorist organization"
Iran shot down a US Global Hawk drone with a surface-to-air missile in June for allegedly violating its airspace, which the United States denies
Seven foreign crew were arrested in the operation carried out on Wednesday night, said Fars news agency, which is considered close to the Guards
The vessel -- the third foreign ship seized by the guards in the Gulf since July 14 -- is suspected of smuggling a large volume of fuel
British authorities detained an Iranian tanker off the UK overseas territory of Gibraltar in early July on allegations it was breaching EU sanctions on Syria
Iran's President Hassan Rouhani said such a force would only make matters worse
Britain has called Iran's capture of the Stena Impero in the Strait of Hormuz on Friday a "hostile act"
Gulf tensions are high, with fears the United States and its longtime foe Iran could stumble into war
The tanker's interception came on the heels of already high tensions in the Persian Gulf as the Trump administration continues its campaign of maximum pressure on Iran
The seizure, announced by Gibraltar's government, could inflame tensions between Iran and the EU just as the UK, France and Germany try to keep Iran from walking away from the nuclear deal