U.S. Secretary of State Marco Rubio reiterated on Wednesday Washington’s stance that Iran must not obtain a nuclear weapon, adding that he would welcome a more active role from China in helping resolve the Mideast conflict.

“Iran is an example of a bilateral issue that is irreconcilable. Their clerical regime wants a nuclear weapon and the world, led by President [Donald] Trump, says that can’t happen,” Rubio told Fox News aboard Air Force One while en route to Beijing to join the U.S. delegation and the president for the first diplomatic visit to China in nine years.

The American top diplomat was referring to the blockade imposed by Iran on the Strait of Hormuz, strangling the global economy.

“We’ve made the argument to the Chinese, and I hope it’s compelling. And they’ll have a chance to do something about it at the United Nations later this week,” he continued.

Despite the close relationship between Beijing and Tehran, Rubio said that “China’s economy is export-driven, meaning their economy is fueled not by what they consume domestically, but by what they make and sell to other countries.

“Economies are melting down because of this crisis in the Strait. They’re going to be buying less Chinese product, and the Chinese exports are going to drop precipitously.”

Speaking to Fox News about the decision to go to war with Iran, Rubio emphasized that the Islamic Republic was ramping up its conventional drone and missile capacity to the extent that it would have been impossible to attack in the future.

“Once they had that, nobody could do anything about their nuclear program. Because they would say, ‘If you attack our nuclear program, we will wipe out six countries in the Gulf region and you won’t be able to defend against it…’ and a year from now they would’ve been at that point,” Rubio stressed.

“The president said that’s an intolerable risk. People are struggling to make that connection, but that connection is very real. They were building such a high number… of drones and missiles that no one could attack Iran because the result would be catastrophic for the region. And once they had that immunity, then they would break out toward a [nuclear]weapon.”