WASHINGTON/DUBAI, Feb 4 - Meaningful talks between the United States and Iran will have to include Tehran's missile arsenal and other issues, U.S. Secretary of State Marco Rubio said on Wednesday, as Tehran vowed that it would only discuss its nuclear programme, not its missiles.

Talks between the countries amid fears of a military confrontation have been planned for Friday, with Iran pushing to restrict the negotiations to discussion of its long-running nuclear dispute with Western countries.

Differences over the scope of the talks and lack of agreement on a venue raised doubts whether the meeting would take place, leaving open the possibility that U.S. President Donald Trump could carry out his threat to strike Iran.

Asked on Wednesday whether Iran's Supreme Leader Ayatollah Ali Khamenei should be worried, Trump told NBC News: "I would say he should be very worried. Yeah, he should be." He added that "they're negotiating with us" but did not elaborate.

"If the Iranians want to meet, we're ready," Rubio said earlier. But he added that talks would have to include the range of Iran's ballistic missiles, its support for groups around the Middle East and its treatment of its own people, besides the nuclear dispute.

A senior Iranian official, however, said the talks would only be about Iran's nuclear programme, and that its missile programme was "off the table." A second senior Iranian official said Tehran would welcome negotiations over the nuclear dispute but that U.S. insistence on dealing with non-nuclear issues could jeopardize the talks.

TALKS MAY MOVE TO OMAN

The meeting was originally planned for Turkey, but a Gulf official, another regional official and Iranian state-affiliated media said the talks were expected to take place in Oman.

Rubio said U.S. envoy Steve Witkoff was prepared for the talks but that the location was "still being worked through" after Iran had previously agreed to a particular format.

Axios later reported, citing two U.S. officials, that the U.S. told Iran on Wednesd...