WARSAW, Poland – Vice President Mike Pence and Secretary of State Mike Pompeo took the White House's aggressive anti-Iran message to a U.S.-sponsored meeting in Poland on peace and security in the Middle East that concluded Thursday.

Pence used his address to the conference in Poland's capital of Warsaw to demand that European countries withdraw from the nuclear deal between Iran and world powers that President Donald Trump's administration has already abandoned.

He urged U.S. allies to back Washington's sanctions on Iran, re-imposed after Trump exited the 2015 accord last year. Long-standing U.S. allies in Europe favor staying in the deal and have sought ways to keep open trade and financial dealings with Iran.

Disagreement over the issue is what partly led to Germany, France and other major U.S. allies not sending their top diplomats to the summit in Poland.

"The authoritarian regime in Tehran represses the freedom of speech and assembly, persecutes religious minorities, brutalizes women, executes gays and openly advocates the destruction of the State of Israel," said Pence.

"Iran endlessly spews hatred against Israel, our most cherished ally."

Pompeo said that the Middle East "can’t achieve peace and security" in that region without first "confronting Iran." But precisely how far the U.S. is willing to take this confrontation or details of its strategy for keeping Iran in check remain wholly unclear.

The U.S. officials spoke as foreign ministers and delegates from more than 60 countries gathered in Warsaw for the summit. However, the conference has drawn rebuke for honing in on Iran while ignoring and downplaying other regional actors.

The topics under discussion included Israeli-Palestinian peace, conflicts in Syria and Yemen, and the turbulent issue of Iran. However, neither Pence nor Pompeo mentioned Saudi Arabia, Iran's regional foe, and a close U.S. ally with a poor human rights record and whose bombing campaign in Yemen has created the world's worst humanitarian disaster. Saudi Arabia has admitted killing The Washington Post columnist Jamal Khashoggi inside its Istanbul consulate.

"It's a very simple equation for me. I'm about make America great again and I'm about America first," Trump said in December in reply to repeated suggestions from media, rights watchdogs and lawmakers that he should be doing more to hold the Saudis accountable. The House easily approved a measure Wednesday that would force the Trump administration to end its military support for the Saudi-led war in Yemen.

More:In rebuke to Trump, House approves measure to force U.S. Yemen withdrawal

Pompeo insisted in Warsaw that "pushing back" against Iran was central to dealing with all the region’s problems, a characterization that will do little to overturn perceptions the Trump administration is determined to see regime-change in Tehran, although Washington has consistently denied it is actively pursuing this course.

The Trump administration accuses Iran of a range of destabilizing activities ranging from support for Shia militant groups in Lebanon, Syria and Yemen to the development of a ballistic missiles program. Washington does not believe that Iran has stopped enriching uranium for its nuclear weapons program despite repeated confirmation from international inspectors that it is abiding by the nuclear accord's terms.

"It's not just a compliance issue," said Pence. "It's that the (Iran) deal was no good."

"Iran is a country you can't rely on, do business with, can't trust," Trump's lawyer, Rudy Giuliani, told USA TODAY on the sidelines of a rally in Warsaw organized by an exiled Iranian opposition group. The former New York mayor is not taking part in the summit, but his views reflect those of many in Trump's inner circle, including National Security Adviser John Bolton, who has long advocated for an aggressive Iran approach.

More:Trump lawyer Rudy Giuliani's side project: Bashing Iran, in Poland

More:Jared Kushner will try to sell Middle East peace plan to U.S. allies amid skepticism, scant details

"An uncontrolled and unintended collapse of the Iranian regime will further destabilize the Middle East and further push back the hopes and aspirations of the Iranian people for democracy and freedom," Pooya Dayanim, an expert on Iran, wrote in a blog post this week for the Atlantic Council, a Washington-based think tank.

"However, Iranians revolted forty years ago and didn’t get the regime they were hoping for. If the Iranian people are to suffer through more sanctions or are to risk life and limb, they need to know why they are doing so and what future awaits them," he wrote, referring to persistent suggestions from Iran hawks in Trump's inner circle that Iran's government is one major protest away from collapsing.

On Monday, Iran marked 40 years of its Islamic Republic.

Tehran has denounced the conference as an American anti-Iran "circus." Russia and China are not attending and Federica Mogherini, the European Union’s foreign policy chief, is also skipping the event. Several high-profile Arab dignitaries are in Poland for the event, but Palestinians – not present – have called for it to be boycotted.

Pompeo's comments echoed saber-rattling remarks by Israel's Prime Minister Benjamin Netanyahu, who drew scrutiny on Wednesday when he made clear the conference is centered on Iran despite the far broader published agenda.

"It is a conference that unites the United States, Israel, many countries in the world, many countries in the region, Arab countries, against Iran’s aggressive policy, its aggression, its desire to conquer the Middle East and destroy Israel," he told reporters.

In an interview with reporters on a Warsaw street, Netanyahu also appeared to say "war" with Iran was a common goal of the summit's participants. Netanyahu used the Hebrew word "milchama," or "war," in his comments. His office later changed its translation and said he was referring to a "common interest of combatting Iran."

Israel is Iran's arch-enemy and Netanyahu has long advocated for a confrontational approach to Iran. However, he has stopped short of calling for war.

Senior White House aide Jared Kushner, who is also in Warsaw, said Thursday that details of the Israel-Palestinian peace plan that he has been working on for months would be released after Israel holds elections in early April.

Brook Hook, U.S. Special Representative for Iran at the State Department, told reporters here that "many of the things we are asking Iran to stop doing are the same things the people of Iran want it to stop doing: investing in foreign adventurism."

In his closing remarks to the media, Pompeo said that in his discussions with delegates over two days in Poland not a "single defender" of Iran emerged.

"Not from Europe, not from Asia, not from the Middle East."