Qatar’s foreign minister will travel to Moscow on Sunday for discussions on the Iran nuclear talks and Russia’s invasion of Ukraine, a source familiar with the visit said. The source said Sheikh Mohammed bin Abdulrahman Al Thani, whose gas-producing country is a key US ally in the Middle East, would meet with his Russian counterpart Sergei Lavrov. Eleven month-old talks in Vienna to revive the 2015 Iran nuclear deal face the prospect of collapse after a last-minute Russian demand forced world powers to pause negotiations despite having a largely completed text. Russia wants guarantees that its…