LONDON: The top US military commander for the Middle East has said his forces have a “very robust range of military options” available to deter Iran, which is expanding its nuclear program and ballistic missile arsenal. Tensions between Iran and the US have been growing in recent weeks as talks in Vienna to curb Tehran’s nuclear program have stalled. “I think … Iran gravely underestimates us if they believe they’re going to be able to continue attacking and cause casualties in Iraq and Syria, and still be able to conduct nuclear negotiations with us without any effect,” Gen. Frank McKenzie told the Financial Times. World powers and Iran were locked in talks on reviving their nuclear deal on Friday, with a European source saying they were working from texts discussed five months ago and Iranian officials saying they were sticking to a tough stance from last week. The talks resumed on Thursday with the US and Israel — which is not a party to the 2015 deal — piling rhetorical pressure on Tehran about the possible economic or military consequences if diplomacy fails. Iran’s top negotiator, Ali Bagheri Kani, said Tehran was standing firm on the position it laid out last week, when the talks broke off with European and US officials accusing Iran of making new demands and of reneging on compromises worked out earlier this year. A European source, speaking on condition of anonymity, appeared to suggest that Iran had agreed to continue talks from where they left off in June. This would be put to the test in the next couple of days, the source said, but made no mention of Iran’s new proposals. Reuters reported that US National Security Adviser Jake Sullivan received a briefing by Pentagon leaders in October on a set of military options available to ensure that Iran would not be able to produce a nuclear weapon, according to a person familiar with the matter. Western nations have become increasingly frustrated with Tehran at the slow pace of diplomacy and its apparent intransigence on the issue. Talks were halted for months when Iran elected its new President Ebrahim Raisi, and Tehran continues to refuse direct talks with the US, instead choosing to use intermediaries. Iran has ramped up its nuclear activity in recent years, including by enriching uranium at levels increasingly close to that required for a nuclear bomb. Tehran insists that all sanctions be lifted before it reverses its nuclear gains. McKenzie said diplomatic engagement remains the “first and best track” to address Iran’s growing nuclear and military capabilities, including missile and drone production. “Let me be very clear: It’s our design and intent that diplomacy lead right now,” he said. “That is the best path forward for everyone and Iran just needs to realize that.” Last week, the UK, France and Germany accused Tehran of reneging on compromises agreed at six earlier rounds of talks this year after Iranian negotiators submitted new proposals that did not appear “realistic.” An anonymous official from the Biden administration told the FT that given Iran’s advancing nuclear program and the slow pace of talks, the US is “laying the groundwork for another path entirely.” The official said: “If diplomacy cannot get on track soon and if Iran’s nuclear program continues to accelerate, then we will have no choice to take additional measures to further restrict Iran’s revenue-producing sectors. We will not get into further specifics at this time.”