BELLINZONA, Switzerland: US Secretary of State Mike Pompeo said Sunday that the Trump administration is ready for unconditional discussions with Iran in an effort to ease rising tensions that have sparked fears of conflict. 

But the United States will not relent in trying to pressure Iran to change its behavior in the Middle East, America’s top diplomat said.

His comments came as the US military conducted exercises in the Arabian Sea with a B-52 bomber and an aircraft carrier dispatched to the region in response to an Iranian threat.

The exercise saw F/A-18 Super Hornets, MH-60 Sea Hawk helicopters and E-2D Growlers from the USS Abraham Lincoln fly with the B-52 bomber, the Air Force said  Sunday.

The aircraft also “simulated strike operations” in the exercise, which took place on Saturday.

In a reminder that tensions are still high, Yahya Rahim Safavi, a top military aide to Iran’s Supreme Leader Ayatollah Ali Khamenei, said Sunday that US military vessels in the Gulf are within range of Iranian missiles and warned warned that any clash between the two countries would push oil prices above $100 a barrel.

Pompeo repeated long-standing US accusations that Iran is bent on destabilizing the region, but he also held out the possibility of talks as President Donald Trump has suggested.

Pompeo made the talks offer during a visit to Switzerland, the country that long has represented American interests in Iran, as part of a European trip aimed at assuring wary leaders that the US is not eager for war.

“We're prepared to engage in a conversation with no preconditions,” Pompeo said. “We're ready to sit down with them, but the American effort to fundamentally reverse the malign activity of this Islamic Republic, this revolutionary force, is going to continue.”

Pompeo’s meeting with Foreign Minister Ignazio Cassis in the southern Swiss town of Bellinzona came amid concerns about the potential for escalation and miscalculation with Iran — a situation that has many in Europe and the Middle East on edge.

Cassis, whose country has been an intermediary between the two before, made no secret of that nervousness.

“The situation is very tense. We are fully aware, both parties are fully aware, of this tension. Switzerland, of course, wishes there is no escalation, no escalation to violence,” he said.

Cassis said Switzerland would be pleased to serve as an intermediary, but not a “mediator,” between the United States and Iran. To do so, however, would require requests from both sides, he said.

Neither he nor Pompeo would say if such requests had been made of the Swiss.

Pompeo thanked Switzerland, which serves as the “protecting power” for the US in Iran, for looking after Americans detained there. Trump administration officials have suggested they would look positively at any move to release at least five American citizens and at least two permanent US residents currently imprisoned in Iran.

Pompeo declined to comment on whether he had made a specific request to the Swiss about the detainees. But, he said the release of unjustly jailed Americans in Iran and elsewhere is a U.S. priority.

Pompeo was in Switzerland on the second leg after Germany of a four-nation tour of Europe in which he is both trying to calm nerves and stressing that the US will defend itself and not relent in raising pressure on Iran with economic sanctions.

Despite the firm stance, Trump has signaled a willingness to talk with Iran's leadership. Iranian officials have hinted at the possibility but also insisted they will not be bulled.

“If they want to talk, I'm available,” Trump said last week, even as Pompeo and the White House national security adviser, John Bolton, were stepping up warnings that any attack on American interests by Iran or its proxies would draw a rapid and significant US response.

The US is sending hundreds of additional troops to the region after blaming Iran and Iranian proxies for recent sabotage to tankers in the Gulf and drone attacks on Saudi Arabia’s oil infrastructure.

Some analysts believe Iran is acting to restore leverage it has lost since Trump withdrew from the 2015 nuclear deal and the US reimposed sanctions that have hobbled Iran’s economy.

Last month, the administration ended sanctions waivers that had allowed certain countries to continue to import Iranian oil, the country's main source of revenue, without US penalties. The U.S. also designated Iran's Revolutionary Guards a “foreign terrorist organization,” adding new layers of sanctions to foreigners that might do business with it or its affiliates.

Despite the US withdrawal, Iran has remained a party to the nuclear deal that involves the five permanent members of the UN Security Council, Germany and the European Union.

On Friday, the United Nations’ nuclear watchdog reported that Iran may be in violation of limits on the number of advanced centrifuges it can use.

Pompeo declined to comment on the findings of the International Atomic Energy Agency other than to say the US is “watching closely” what is going on in Iran.