U.S. President Donald Trump on Monday warned Iran that it would face consequences if it failed to reach an agreement in the upcoming talks. Speaking to reporters aboard Air Force One while returning to Washington, Trump said he would be indirectly involved in the discussions and cautioned that Iran would not want to face the outcome of refusing a deal. The meeting between the United States and Iran is scheduled for Tuesday in Geneva, mediated by Oman.

The talks come after months of heightened tensions following Iran’s crackdown on anti-government protests and its firm stance on its nuclear program. The United States and several European countries have expressed concern that Iran’s nuclear activities could be aimed at developing weapons, an allegation Tehran continues to deny. Washington has also sought to include Iran’s ballistic missile program and its support for armed groups in the Middle East in the negotiations.

Iran’s Foreign Ministry stated on Monday that the U.S. position on the nuclear issue had become more realistic. A previous attempt at dialogue collapsed after Israel launched a surprise attack on Iran, sparking a 12-day war that later saw U.S. airstrikes on Iranian nuclear facilities.