WASHINGTON (AFP) - Afghanistan's Foreign Minister Rangeen Dadfar Spanta said Thursday that Pakistan should be the world's main concern as the two countries held a three-way "war on terror" review with the United States. US President Barack Obama is sending 17,000 more troops to Afghanistan, putting a new focus on fighting extremism in the mountainous nation as he winds down the controversial US military involvement in Iraq. Foreign Minister Spanta welcomed the deployment but said that "the main problem we have to face" lies across his nation's border. "My thesis is that the main threat centre for instability in the world is not Iraq, it is not Afghanistan, it is much more Pakistan," Spanta said in Washington amid three-way talks with US and Pakistani counterparts. He said Pakistan was worrying because of its giant population and because of its nuclear weapons. "If Pakistan becomes a failed state, it is a serious threat for you, for us and for the entire region," Spanta said at the Centre for American Progress, a think-tank. But Spanta said that Afghanistan had confidence in Pakistan's civilian government of President Asif Ali Zardari, who last year replaced military leader Pervez Musharraf. Spanta appealed to the United States and other powers to show support to the Zardari government. There is "a lot of commonality between Afghanistan and the civilian government," Spanta said. "This is a very new phenomenon in our bilateral relations."