GENEVA — A senior Iranian official is responding sharply to warnings that Washington is ready to quit nuclear talks unless Tehran agrees to a deal that demonstrates it does not want atomic arms.

Ali Akbar Velayati says staying or leaving “depends on the Americans.”

Velayati was responding Sunday to U.S. Secretary of State John Kerry. Kerry said President Barack Obama was “fully ready” to pull the U.S. out before agreeing to a deal leaving Tehran with potent nuclear arms-making ability.

Their exchange may be an attempt to play to their home audiences but could also signal difficulties at the talks with only a month to go to a late-March deadline for a first-stage deal.

Iran says it does not want such weapons but is negotiating in hopes of sanctions relief.