Confrontation between the West and Iran becomes "more possible," as Tehran continues advancing towards possessing a nuclear weapon, US Secretary of State John Kerry told ABC News on Tuesday."If [Iran] keeps pushing the limits and not coming with a serious set of proposals or prepared to actually resolve this, obviously the risks get higher and confrontation becomes more possible," Kerry said.Kerry was speaking to ABC News while in Qatar, on the last stop of his first visit to the region as secretary of state. In a previous tour stop in Saudi Arabia, Kerry stated there was a "finite" time for nuclear talks with Iran."The window for a diplomatic solution simply cannot by definition remain open indefinitely,” Kerry said, echoing previous statements made by US Vice President Joe Biden.The secretary of state did not, however, state how long Washington would be willing to continue to negotiate with the Iranians.Reuters contributed to this report.Despite that, Kerry stated US President Barack Obama prefers the diplomatic solution and to avoid considerations of military action. "Lines have been drawn before and they've been passed. That's why the president has been so definitive this time. This is a very challenging moment with great risks and stakes for everybody because the region will be far less stable and far more threatened if Iran were to have a nuclear weapon," Kerry said.Kerry emphasized the threat extends beyond the possibility of Iran using its nuclear weapon on its enemies, and that Tehran simply having nuclear weapon would "spur a nuclear arms race" in the region.