AMNA NAWAZ: Welcome to the "News Hour."

Iran's top national security official today warned the U.S.

that it would strike American bases beyond the Gulf, including in Europe, if the United States resumes airstrikes.

GEOFF BENNETT: The warning comes a day after three men were indicted in New York for allegedly plotting to attack U.S.

Air Force planes at a base in England.

One of the suspects with deep ties to Iran allegedly directed the plot from a federal detention center in New York.

The threat prompted the U.S.

to relocate bombers from the British base back in September.

Nick Schifrin has more.

NICK SCHIFRIN: The attack was livestreamed and set to propaganda music, a man throwing a Molotov cocktail at a media company critical of the Iranian regime, as, 1,500 miles away, one of the organizers watched and recorded.

It was one of multiple terrorist attacks across Europe in March and April, including the stabbing of two Jewish Londoners and another arson attack on a Jewish-owned charity that the U.S.

now says was orchestrated remotely by this man, Mohammad Baqer Saad Dawood Al-Saadi, seen here in 2024 with machine guns behind him.

The U.S.

accuses Al-Saadi of working on behalf of Iran's Islamic Revolutionary Guard Corps and the Iranian proxy group Kataib Hezbollah based in Iraq.

Earlier this year, the U.S.

alleges he planned or promoted 18 terrorist attacks in Europe, as well as a plot against a New York synagogue.

He was then arrested in August by Turkey and extradited to the United States.

But that didn't stop his plots.

The U.S.

alleges that, while behind bars in Brooklyn, he directed and paid fellow militants in the United Kingdom to drive these white vans to a British air base.

The vans pretended to be from a gas delivery and swimming pool supply business, but were actually surveilling the Royal Air Force base at Fairford.

The U.S.

alleges the plotters had bought shrapnel and chemicals that could be used for a bomb.

The plot forced the U.S.

to evacuate B-1s that had been used to bomb Iran.

And the U.S.

alleges Al-Saadi initiated the attack while he was in the Brooklyn prison while speaking to his immediate family using code words.

COLIN CLARKE, The Soufan Center: This is something that really hearkens back more to things like gangs or the mafia, right?

So, allowing mafia members or gang leaders to have conversations that are then monitored, surveilled, and acted upon.

NICK SCHIFRIN: Colin Clarke is the executive director of The Soufan Center, which focuses on terrorism.

He says the plot against Fairford highlights Iran's willingness to use terrorism and other asymmetric attacks to fight what it considers a decades-old war against the U.S.

and Israel.

COLIN CLARKE: It just shows that the Iranians are going to continue to be relentless in their pursuit of what they see as revenge, even if we were to reach a deal tomorrow, which, by the way, is highly unlikely.

NICK SCHIFRIN: And in response to the 2020 U.S.

strike that killed powerful Iranian commander Qasem Soleimani, the U.S.

has long accused Iran of trying to assassinate senior American officials.

COLIN CLARKE: The United States killed Qasem Soleimani in January 2020 and helped the Israelis find and kill the supreme leader of Iran.

And so all bets are off when it comes to Iranian vengeance.

This is something we're going to see for the foreseeable future.

NICK SCHIFRIN: And this week's indictment shows, to seek that vengeance, Iran will increasingly turn to proxies, including the Iraq-based Kataib Hezbollah.

OMAR AL-NIDAWI, Atlantic Council: Most of the Kataib Hezbollah operations in the past have been crude military operations, lobbing rockets, short-range rockets against American bases.

NICK SCHIFRIN: Omar Al-Nidawi is with the Atlantic Council's Iraq Initiative.

OMAR AL-NIDAWI: This is the first foray of -- by Kataib Hezbollah into attacks, terror-style attacks, sophisticated-style -- sophisticated attacks on European soil.

NICK SCHIFRIN: And why is that significant?

OMAR AL-NIDAWI: It definitely pulls Iraq closer into the conflict.

It also highlights Iran's increasing reliance on these factions.

NICK SCHIFRIN: A plot thwarted this time that American officials fear Iran could try to repeat.