However Israelis, Americans and Britons feel about the decertification of the Iran Deal – it is now a reality. US President Donald Trump’s move signals a policy that favors bellicose style over substance, leaving Europe to mete out moderation. The UK’s Labour Party, steeped in cautious, anti-interventionist sentiment, risks being drawn into a Trumpian isolation if it fails to produce a coherent line on a hostile Iran. It may still be in opposition, but the party has to prove itself on foreign policy if it is to be trusted by allies in the Middle East.When Labour’s Shadow Foreign Secretary Emily Thornberry stood before Parliament to condemn Trump’s withdrawal from the deal the party proved it had a long way to go in this respect. Thornberry made a nod to Iran’s presence in Syria and Yemen, but the bulk of her rancor was directed against Trump. Accusations of “idiocy” and “diplomatic sabotage” are excellent and not totally inaccurate soundbites, but praying that Tehran show “patience and resolve” shows something of a disconnect from reality on the ground.The Labour Party still bears the scars of the 2003 invasion of Iraq. It is these scars that make the appellation “Blairite” a smear among Jeremy Corbyn’s supporters. It is these same scars that allowed Corbyn supporters to rush to his defense after his stumbling approach to condemnation of Russia after the Skripal Affair. But this is a stumble that has turned into a limp for the party.A lack of nuance on foreign policy on the Middle East has led Labour to continue to look to the UN Security Council for a solution to Syria. This is a forum where Russia’s support of Assad’s murderous regime will not be checked. The deadlock in it is self-evident, and makes this call by Labour procedurally important. Still, it amounts to foot-dragging in practice, and there is no great morality in hesitating while crises mount.This is just the same when it comes to Iran: Labour cannot avoid serious international diplomacy forever. French President Emmanuel Macron has been right in heading up the efforts of European signatories in keeping the US in the nuclear deal. This entails further negotiation and diplomatic effort. The 35-day consultation period built into the deal, and the time before US Congress can re-impose sanctions is key to this. Journalists, activists and think-tankists can condemn and kick their limbs, but it is down to politicians to shift and adapt. An infantile response shows this may still be beyond the Labour Party and its pick for shadow foreign secretary.The role of a parliamentary opposition is not merely to criticize a ruling party. Its purpose is to provide meaningful alternatives that carve it out a place as a government in waiting. This is a task that involves both tone and practice. On the foreign policy front, Labour currently fails both tests.Iran is certainly a threat in the Middle East, as Thornberry states. For Israelis this fact is more present than ever, as Israel’s air force trades blows with Iranian proxies in Syria. The prospect of it becoming a nuclear power and resuming high-level enrichment is immensely destabilizing. These very present possibilities make checks and balances on its military activities vital if all sides are to avoid a costly war. A fact all the more crucial with a US administration that puts this possibility firmly on the table. As these matters become all the more pressing, Labour’s refusal to engage verges on irresponsibility.The party’s supporters must accept that its anti-interventionism has led it into the same isolation that it sees in Trump. Abdicating responsibility on moral grounds is closer to sophistry than policy. It is also the luxury of an opposition whose prospects of power continue to dwindle.But this is not just a malady that affects Labour. One would be hard pressed to find a government at the moment with a clear line on Iran. Most face the same conundrum of attempting to safeguard both their countries’ business interests and their own (and the region’s) security. The Iran deal did both imperfectly, but represented a markedly better solution than the chaos we now face. This is not an issue of Left against Right or hawks versus doves: the security of the Middle East and its inhabitants is at stake.Labour understands about half of this. Talking about “international security” on the British Left has become somehow anathema since Iraq. Islamic State (ISIS) was perhaps excepted from this because of the incredibly heinous crimes it committed, but even there Britain’s response has been far from committed. As Europe and the US fail to take charge, they have yielded ground to Russian President Vladimir Putin, Iranian Supreme Leader Ali Khamenei and generalissimo Qasem Soleimani.Britain and its opposition cannot retreat into its shell when the going gets tough. Whether Labour realizes or not, the UK is a major international power with a role in shaping regional policy. Carrying the albatross of Iraq forever may well change this, leaving less room for shaping and honing international policy on Iran. In the words of Blackadder’s General Melchert, “security” is not a dirty word.The author is a Tel Aviv-born graduate of Oxford University in Persian studies and an MSc candidate in conflict studies at the London School of Economics. He has extensive experience in counter-terrorism and foreign policy research in Jerusalem, London and Washington, DC. Follow him @Daniel_Amir1.