Shanahan, who was named Acting Defense Secretary to replace James Mattis after he resigned, reportedly met with Congressional officials alongside Secretary of State Mike Pompeo.
Oman's Foreign Minister Yusuf bin Alawi sat down with Zarif in Tehran in what was interpreted as a mediation drive led by a country that has traditionally shuttled between Iran and the United States to try to end the two arch foes' decades-long hostilities.
The sources, who are familiar with USA national security assessments and spoke on condition of anonymity, said the United States was still trying to establish which militia fired the Katyusha rocket on Sunday and the extent, if any, of Iranian involvement.
Bolton said that this was "i$3 n response to a number of troubling and escalatory indications and warnings" from Iran.
Mr Zarif added Iran is "not interested in escalation". Despite favoring diplomacy over disputed issues, he is now opposed to any negotiations with the United States, said Rouhani.
The Iranian president said that the reason Iran has been reluctant to walk away completely from the 2015 nuclear deal struck with the US under the Obama administration, also known as the Joint Comprehensive Plan of Action, is that it would lead to more economic pressure on Iran, IRNA reports. It's not for a president to say it and start it.
The announcement came days after Tehran gave European signatories to the deal 60 days to rescue it by finding ways around sanctions reimposed by the U.S. after President Donald Trump pulled out of the agreement previous year.
US Commerce Department Lifts Restrictions on Huawei
Huawei is one of a number of phone manufacturers who use the Google-developed Android operating systems on its phones and tablets. However, the U.S. companies now need to seek permission from the government before doing any business with Huawei.
Flight deck of the United States aircraft carrier USS Abraham Lincoln (CVN 72) is seen as sailors sweep the deck for foreign object and debris (FOD) walk-down on the flight deck of the Nimitz-class aircraft carrier USS Abraham Lincoln (CVN 72) in Arabian Sea, May 19, 2019. The Pentagon has already sent bombers to the region.
Trump has blown hot and cold over Iran, leading many in Washington to fear he is rushing to conflict, but then indicating that he has no desire to embroil the United States in another distant war. Iranian officials said on Monday that they had increased by fourfold the production of low-enriched uranium - although the increase remains for the moment within the restrictions of the deal.
Nuclear officials have revealed that Iran quadrupled its uranium-enrichment production capacity amid tensions with the U.S. over Tehran's atomic programme.
Iranian President Hassan Rouhani speaks in Tehran, Iran, January 10, 2019.
However, by increasing production, Iran soon will exceed the stockpile limitations set by the accord. It was a message to the Europeans to act to save the nuclear deal before Iran breaks the agreement by moving past the 300 kilograms of enriched uranium it is allowed to hold under the JCPOA.
Mr Trump reinstated the sanctions a year ago after abandoning the nuclear deal.
"On the whole, the future of the Joint Comprehensive Plan of Action (JCPOA) on Iran's nuclear deal gives rise to concerns", the ministry said. Unlike Iraq under Saddam Hussein and Afghanistan under the Taliban, Zibakalam told Arman daily, Iranians' support for their government will pose a key challenge to the USA military. Sherman warned that reckless behavior by the Trump administration in Iran is hurting credibility and undermining moderates in the country, according to a person in the room who was not authorized to discuss the private meeting.
Yemen's Iran-aligned Houthi group claimed responsibility for attacking the pumping stations. Tensions between Washington and its Sunni Muslim Gulf Arab allies on one side and Tehran and its Shia Muslim proxies on the other have been flaring for weeks.
Almost half - 49% - of all Americans disapprove of how Republican Trump is handling relations with Iran, the poll found, with 31% saying they strongly disapprove. While the United States has pulled out of this deal in 2018, other signatories have tried to keep it going.