Iran's president said Thursday he would not plead with opponents of Tehran's nuclear program in order to avoid sanctions as Russia and the United States said new measures might be necessary. Mahmoud Ahmadinejad, who Wednesday called US President Barack Obama a nuclear-armed “cowboy”, said Iran would “try to make an opportunity out of sanctions” rather than change its stance to avoid them. “We do not welcome the idea of threat or sanctions, but we would never implore those who threaten us with sanctions to reverse their sanctions against us,” he was quoted as saying by the official news agency IRNA. Ahmadinejad was speaking as Obama and Russian President Dmitry Medvedev signed a nuclear arms reduction treaty in Prague. The two were “working together at the United Nations Security Council to pass strong sanctions on Iran”, Obama said. Medvedev said he was unhappy with Iran's stance over its nuclear program which the West believes is aimed at developing atomic weapons. “Tehran is not reacting to a range of suggested constructive compromise agreements. We can't close our eyes to this. That is why I do not exclude that Security Council will have to examine this question again,” Medvedev told reporters. Obama is hoping to persuade Russia and China – both Security Council veto holders – to drop their traditional reluctance to the new sanctions. His campaign is likely to continue next week when both Medvedev and Chinese President Hu Jintao attend a summit on nuclear security in Washington. While dismissing the sanctions threat, Iran has also warned against any military steps against its nuclear program. After several warnings that it would hit back at Israel if attacked from there, Iran's military chief said Thursday he would target US forces stationed in the Middle East if Washington attacked. ? Reuters __