There are moments in history when the Special Relationship really matters. The Falklands War, the Gulf War, the response to the 9/11 attacks on New York and Washington, the NATO-led operation against the Taliban and al-Qaeda in Afghanistan are prime examples. The world is a better and safer place when the United States and the United Kingdom stand together on the world stage, especially when confronting dangerous adversaries such as the increasingly aggressive and menacing tyranny in Tehran.

The Iranian regime has the blood of American and British servicemen in Iraq on its hands. It threatens to wipe Israel off the “global political map”, continues to harbor ambitions to be a nuclear weapons power, and arms and funds terror groups across the Middle East. It has even plotted a series of terror attacks on European soil in recent years.

Iran is also a dictatorship that brutalizes its own people, and tramples upon the very principles the United Nations is founded upon. This country simply cannot be allowed to become an even greater threat to international security.

Today, America’s Secretary of State Mike Pompeo heads to the United Nations Security Council, where he is expected to announce that the United States will invoke “snapback sanctions” against Iran, following the refusal of the Security Council last week to extend the U.N. arms embargo which has been in place since 2007.

With the lifting of the embargo in October, the world’s biggest state sponsor of terror will be free to purchase deadly weaponry from across the world, which it will undoubtedly deploy in Syria and Yemen, as well as use to arm terrorist groups such as Hamas and Hizbollah. In the words of U.S. Ambassador to the United Nations Kelly Craft, the U.N. vote will “unlock Iran’s access to combat aircraft, attack helicopters, warships, tanks, missile systems, and other advanced weapons.”

The snapback sanctions, which the U.S. can impose through United Nations Security Council Resolution 2231, will prevent that from happening. Even though the US formally withdrew from the failed Iran nuclear deal in 2018 (Joint Comprehensive Plan of Action), it can still execute the snapback process in accordance with the provisions of Resolution 2231, which endorsed the Iran deal back in 2015. As Richard Goldberg, the former Director for Countering Iranian Weapons of Mass Destruction at the White House National Security Council has noted, the Trump Administration has every right to invoke the snapback option:

“The United States is defined forever as a “JCPOA participant” in a binding Security Council resolution for the purpose of snapback. Whether the resolution was drafted this way intentionally or not makes no difference. Whether the administration of former President Barack Obama carefully negotiated the wording of UNSCR 2231 to protect a U.S. snapback right in perpetuity, or the Trump administration took advantage of a glaring oversight, the outcome is the same. The resolution, a document legally independent of the Iran deal itself, gives the United States the right to trigger the snapback if Iran breaches its commitments.”

It is time for the United Kingdom to step up to the plate at the United Nations and stand with the United States. The U.K. abstained in last week’s vote along with Germany and France, refusing to confront the Chinese and Russians, who voted to end the arms embargo against Tehran. It is time for Great Britain to truly break free of the ghost of the European Union’s weak and ineffective Common Foreign and Security Policy.

In the Brexit era, Britain should not feel obligated to side with Brussels, whose instincts on Iran and so many other issues including dealing with China, are forged in an appeasement mentality, one that is driven in some quarters by both financial interests and anti-Americanism.

Together with the United States, Brexit Britain must be a standard bearer for freedom and a powerful opponent for the likes of Iran, China and Russia. It is hugely disappointing that the U.K. opted not to vote in support of maintaining an arms embargo against one of the deadliest dictatorships in the world, one that has brutally taken British lives, and talks of genocide against the people of Israel.

In the battle between good and evil, there can be no middle ground. Iran’s rulers thrive off divisions in the West, and the desire on the part of some European capitals to continue to do business with one of the worst human rights violators in the world.

Today, Britain faces a choice at the U.N. Work with its closest friend and ally the United States to hold Iran to account, or join the European appeasement lobby that strengthens the position of Tehran’s friends in Moscow and Beijing. This is a major leadership moment for Boris Johnson, who holds a deep distrust of Iran’s intentions, and wants to ensure that Iran’s ambitions are constrained. It is impossible to imagine the Prime Minister’s heroes, Margaret Thatcher and Winston Churchill, walking away from the United States in a similar situation.

As history has shown on so many occasions, the Special Relationship is fundamentally important to British interests, and is even more invaluable to the U.K. outside of the E.U. On several fronts, the partnership between London and Washington is being strengthened, with a large-scale U.S.-U.K. free trade deal now on the horizon, and the U.S. and British governments working closely to confront the growing challenge posed by China; from Hong Kong to the South China Sea.

Great Britain and the United States should be standing shoulder to shoulder against the Iranian threat at every opportunity. Today is one of those key times to do so.