US president Barack Obama has said sanctions on Iran are having "enormous bite," but he still wants to work with Russia and China to find more ways of putting pressure on Tehran over its nuclear programme.
At a news conference following the Asia-Pacific Economic Co-operation (Apec) summit in Hawaii, Mr Obama made it clear that no options were off the table regarding Iran.
At the summit, the US leader met Russian and Chinese leaders to discuss a new report from the UN watchdog agency that included evidence Iran's programme is working on research and design efforts to develop a nuclear bomb.
Mr Obama said Russia and China shared America's goal of making sure Iran does not build the bomb, although both countries have said they oppose new sanctions.
Following questions from journalists, Mr Obama added that the interrogation technique known as waterboarding constitutes torturing, in direct opposition to the views of Republican presidential candidates who say they would reinstate the practice.
Mr Obama called waterboarding "torture" and said it was "contrary to America's traditions".
Republicans Herman Cain and Michele Bachmann said during a Republican debate on Saturday that they would reinstate the technique that former president George W Bush authorised and Mr Obama banned.
The practice simulates drowning and is viewed as torture by many.
At the summit earlier, US officials said Canada and Mexico have both expressed interest in joining a US-backed trans-Pacific trade initiative.
The White House said Mr Obama welcomed Canadian Prime Minister Stephen Harper's indication his government would begin talks on joining the so-called Trans-Pacific Partnership.
It added that together with similar announcements by Japan and Mexico, the news shows the "broadening momentum and dynamism" of the effort to work toward an eventual region-wide free trade zone.
The US trade representative, Ron Kirk, also welcomed the positive overtures from America's "neighbours and largest export markets".