A senior US official on Monday raised the spectre of further attacks in the region despite Washington’s enhanced military presence, saying the “maximum pressure” campaign against Tehran cannot prevent violent action by Iran or its proxies. In tacit recognition of criticism that the United States was compromising the effectiveness of its campaign by acting too unilaterally, US diplomat Brian Hook said the importance of the Strait of Hormuz to world energy supplies demands a “global response” to what he termed Iranian threats. Mr Hook’s comments came as US Secretary of State Mike Pompeo travelled to the UAE and Saudi Arabia and President Donald Trump called on China and Japan, major consumers of Middle East oil, to take more responsibility for protecting shipping lanes. Speaking a day after a drone attack on Saudi Arabia's Abha airport by the Iranian-backed Houthi militia that left one dead and at least 21 injured, Mr Hook told reporters in a phone briefing that more “asymmetrical attacks” by Iran and its “surrogates” cannot be ruled out. Mr Hook, a lawyer who is the US Special Representative for Iran, said US sanctions “weakened Iran’s military spending and also its ability to support its proxies”. He did not elaborate on which targets could be hit next. “Iranian economic mismanagement and American sanctions have created a circumstance where they do not have the money they used to. That does not mean we have eliminated Iran’s abilities to conduct asymmetrical attacks. It is just the nature of modern terrorism.” Aamid the current tensions in the Gulf, asymmetrical attacks have come to refer to limited attacks on specific targets that fall short of a clear offensive action directly attributable to a state actor. These include Houthi attacks on Saudi energy facilities and other civilian infrastructure, the attacks on several oil tankers in the Strait of Hormuz over the past two months – which Washington and Saudi Arabia have blamed on Iran but Tehran has denied – and the Iranian downing of a US surveillance drone Tehran said was flying over Iranian territory. Washington insists the drone was over international waters when it was shot down last Thursday. Mr Hook kept up the US offer to negotiate a new nuclear deal with Iran but said there was no backchannel diplomacy underway with Tehran. He called on US allies still committed to the deal – the UK, Germany and France – to reject what he called nuclear blackmail by Tehran. “Iran knows how to reach us. Until then our campaign of diplomatic isolation and maximum economic pressure will intensify,” he said. Last year the US withdrew from the 2015 Iran nuclear deal, known as the Joint Comprehensive Plan of Action, which Mr Hook said allowed Iran to pursue regional instability and was “silent” on Iran’s ballistic missiles and the deployment of its regional proxies. “It does say in the preamble that the plan of action will contribute to regional peace and stability. If only that was the case,” Mr Hook said, repeating US offers of lifting of all sanctions and restoring diplomatic ties with Tehran if a new deal is struck. He described Iran’s non-proliferation commitments under the current deal as “modest and temporary”, coming “at the expense of missile proliferation, regional aggression, human rights abuses the arbitrary detention of dual national citizens”. “We have made it clear that we are looking for a deal that is truly comprehensive,” Mr Hook said, making an apparent nod to the possibility of a multilateral response towards potential destabilisation of oil supplies, which critics of the Trump administration say has been lacking in the US approach. “This is a global challenge that requires a global response,” said Mr Hook, who was on a tour of Gulf states last week. “I talked with countries in the region on how we can enhance maritime security. There are a number of ideas that I think a number of nations are considering.”