The tussle between Baghdad and Iraq's autonomous Kurdish region after the latter announced new draft constitution pose major difficulties and could disrupt crude supplies from the crucial oil-hub city of Kirkuk. The Kurds have long striven to expand their northern territory beyond its current three provinces to other areas where the population was historically Kurdish. Kurdistan, with its capital in Arbil in northern Iraq, has its own flag which is raised beside the federal flag, and also has its own slogan, national anthem and national day. In his visit to Iraq, US Vice-President Joe Biden warned Iraqi officials that Washington would politically disengage if sectarian and ethnic strife resumed as he warned of a "hard road ahead". "The President [Barack Obama] and I appreciate that Iraq has travelled a great distance over the past year but there is a hard road ahead if Iraq is going to find lasting peace and stability. It's not over yet," he said after talks with Iraqi Prime Minister Nouri Al Maliki. "There are still political steps that must be taken and Iraqis must use the political process to resolve their remaining differences and advance their national interest and we stand ready if asked, and if helpful, to help in that process." A senior US official told reporters that Biden had also threatened that Washington would disengage politically if violence in Iraq spiked. "If it actually reverts to violence then that would change the nature of our engagement. He was quite direct about that," the official told reporters. "He also said if by the actions of different parties in Iraq, Iraq were to revert to sectarian violence or engage in ethnic violence then that's not something that would make it likely that we would remain engaged." Biden said: "In recent days the enemies of Iraq have once again tried to reignite sectarian violence through several deadly bombings. They will fail, they will fail because Iraq's future belongs to those who are attempting to build Iraq, not those who are attempting to destroy it." Maliki said: "I have seen very clearly the keen determination from the vice-president and his administration to support Iraq on a political level and in the democratic area and a great readiness to give us or to lend anywhere we ask a lending hand and support. In respect to the sovereignty of both countries we are looking also for ways for exchange that support the interests of both parties." Keep up with the latest business news from the region with the Emirates Business 24|7 daily newsletter. To subscribe to the newsletter, please click here .