WASHINGTON, Feb. 12 (Xinhua) -- U.S. President Barack Obama on Tuesday night vowed to prevent Iran from acquiring nuclear weapons, calling for the Islamic republic to take the opportunity for a diplomatic solution.
"We will do what is necessary to prevent them from getting a nuclear weapon," the president said in his prime-time State of the Union address to the joint session of the Congress.
"The leaders of Iran must recognize that now is the time for a diplomatic solution, because a coalition stands united in demanding that they meet their obligations," he added.
As Iran agreed to start fresh talks with the so-called P5+1 group of Britain, China, France, Russia, the United States and Germany on Feb. 26 in Kazakhstan, the Obama administration has time and again urged its arch-rival to engage in "substantive" negotiations over its disputed nuclear program in return for eased sanctions.
New U.S. Secretary of State John Kerry said last week that the "window for diplomacy" was still open and Washington would continue its dual-track policy of both pressure and engagement in dealing with Iran.
U.S. Vice President Joe Biden offered early this month direct bilateral talks with Tehran, but was turned down by Iran's Supreme Leader Ayatollah Ali Khamenei on the grounds that the Obama administration has shown "ill-will" by imposing "paralyzing sanctions to paralyze the Iranian nation."
Iran insists on the peaceful nature of its nuclear program, while the West regards it as a cover for making nuclear bombs.
Iran and the six powers held three rounds of talks last year but made no breakthrough.