Washington : President Donald Trump on Monday repeated his insistence that Iran will not be allowed to obtain a nuclear weapon, amid mounting tension over the US killing of a top Iranian commander. Writing in all-caps, the US leader tweeted: “IRAN WILL NEVER HAVE A NUCLEAR WEAPON!” The tweet came a day after Tehran announced it was further winding down observance of parts of an international deal struck to ensure that the country does not secretly develop a nuclear weapon under cover of its civilian nuclear industry. Trump withdrew the United States from the 2015 deal negotiated under his predecessor Barack Obama. Last year, Iran resumed uranium enrichment, reporting a tenfold increase in production. Tensions between the two countries spiked last week when a US drone strike in Baghdad killed Qasem Soleimani, the head of the Iranian Revolutionary Guards’ Quds Force. While Iran has threatened retaliation for the killing, Trump has warned that the US will strike “very hard and very fast” at as many as 52 Iranian targets if the Islamic republic does attack US personnel or assets. Huge crowds turned out Monday in Iran for the 62-year-old commander’s funeral, while in neighboring Iraq, parliament has voted to expel some 5,200 US troops stationed in the country. Trump’s tweet did not add any details about steps he was considering to prevent Iran from reviving its nuclear program. Iran has always denied any military dimension to its nuclear project. US President Donald Trump doubled down Sunday on a threat to attack Iranian cultural sites despite accusations that any such strike would amount to a war crime. After his top diplomat, Mike Pompeo, had insisted that any military action would conform to international law, Trump said he would regard cultural sites as fair game if Iran resorted to deadly force against US targets. “They re allowed to kill our people, they re allowed to torture and maim our people, they re allowed to use roadside bombs and blow up our people and we re not allowed to touch their cultural site? It doesn t work that way,” Trump told reporters. “If they do anything there will be major retaliation.” His comments on his return from a break in Florida followed a welter of criticism over a Tweet on Saturday night in which he said sites which were “important to… Iranian culture” were on a list of 52 potential US targets. Tehran s foreign minister had reacted to those initial comments by drawing parallels with the Islamic State group s destruction of the Middle East s cultural heritage. And as Twitter was flooded with photos of revered Iranian landmarks in ancient cities such as Isfahan under the hashtag #Iranian Cultural Sites, leading US Democrats said the president would be in breach of international protocols if he made good on his threat. “You are threatening to commit war crimes,” Senator Elizabeth Warren, one of the top Democrats hoping to challenge Trump in November s election, wrote on Twitter. “We are not at war with Iran. The American people do not want a war with Iran.” “Targeting civilians and cultural sites is what terrorists do. It s a war crime,” added fellow Senator Chris Murphy. In a flurry of interviews on the Sunday talkshows, Secretary of State Pompeo said the US would not hesitate to hit back hard against Iran s “kleptocratic regime” if it came under attack, but pledged that any action would be consistent with the rule of law.