Former Canadian prime minister Stephen Harper has added his name to a full-page ad in the New York Times with a message to U.S. President Donald Trump: "You are right about Iran."

The ad, titled "Mr. President, you are right about Iran" in bold letters, is signed by Harper, former Australian prime minister John Howard, Nobel Peace Prize winner and former Northern Ireland first minister David William Trimble, and other former politicians and writers, including John Baird, former Canadian foreign affairs minister.

Foreign Affairs Minister Chrystia Freeland on Canada's relationship with Iran and former prime minister Stephen Harper's decision to speak out in support of U.S. President Donald Trump's decision to abandon the Iran nuclear deal. 1:27

The A5 ad ran Wednesday, a day after Trump announced the U.S. is pulling out of the landmark nuclear accord with Iran.

"Iran is a danger to us, to our allies, to freedom," the text says. "We stand alongside you in ending the dangerous appeasement of Iran and making all and any action required to stop Iran going nuclear, help its people, halt its spreading of terror and achieve peace and stability in the Middle East and among all peoples and nations."

Harper's government suspended diplomatic relations with Iran in 2012, expelling diplomats and closing the embassy. The Trudeau government campaigned on a promise to restore diplomatic relations with Iran, but talks are frozen pending the release of dual Iranian-Canadian citizen Maryam Mombeini.

Wow. Full page ad in <a href="https://twitter.com/nytimes?ref_src=twsrc%5Etfw">@nytimes</a> signed by <a href="https://twitter.com/stephenharper?ref_src=twsrc%5Etfw">@stephenharper</a> and former Australian PM John Howard <a href="https://t.co/ABNQdCe4Pf">pic.twitter.com/ABNQdCe4Pf</a> —@nspector4

Foreign Affairs Minister Chrystia Freeland said Harper is entitled to express his views.

"This is, though, an opportunity for me to be very clear that the government of Canada's position is that we regret the U.S. decision on the [Joint Comprehensive Plan of Action.] We believe the JCPOA is an important and useful agreement," she told reporters in Washington.

Freeland said she spoke to her U.K. counterpart, Boris Johnson, Thursday morning about a path forward to prevent Iran from obtaining nuclear weapons.

The Prime Minister was in Chicoutimi Thursday 0:47

On Wednesday, Trudeau told reporters the 2015 agreement that was negotiated by the world's major powers wasn't perfect, but it helped prevent that country from developing a nuclear weapon.

"We will respect the capacity of individual countries to make their decisions about foreign policy," Trudeau said.

"But for Canada's purpose, we make our decisions around foreign policy here in Ottawa, not in Washington, not elsewhere."

The prime minister said he expects the Iran decision to be discussed when he hosts Trump and their G7 counterparts in Quebec at their annual summit next month.

Trudeau echoed his comments at a press conference in Quebec on Thursday.