Rubio confirms Iran demanded venue change for nuclear talks

"We thought we had an established forum that had been agreed to in Turkey. It was put together by a number of partners who wanted to attend and be a part of it," Rubio said when taking questions from reporters on Wednesday. 

"I saw conflicting reports yesterday from the Iranian side saying that they had not agreed to that. So, that's still being worked through. At the end of the day, the United States is prepared to engage in, has always been prepared to engage with Iran."

Rubio would not say what topics had been agreed on. Rather, he laid out matters that, in his view, would need to be discussed in order for the meeting to "actually lead to something meaningful." The topics on Rubio's list include the range of Iran's ballistic missiles, its sponsorship of terror organizations, its nuclear program and the treatment of its people.

On Tuesday, the U.S. military shot down an Iranian drone after it "aggressively approached a U.S. Navy aircraft carrier with unclear intent," a U.S. Central Command spokesman told Fox News.

Iran later claimed that the drone was conducting surveillance as part of a "routine and lawful mission over international waters."

Fox News Digital's Michael Dorgan, Greg Norman-Diamond and Liz Friden, and Fox News' Aishah Hasnie contributed to this report.