President Barack Obama offered Xi Jinping a warm welcome at the White House on Thursday, greeting his Chinese counterpart with a "ni hao," or hello, at the start of a tricky state visit. The pair kicked off Xi's first state visit by shedding their ties and strolling out of the West Wing and across Pennsylvania Avenue to Blair House. Officials hope that by starting with a casual meeting the leaders of the world's two pre-eminent military and economic powers will find time for a less staid exchange of views. On Friday Xi will be offered a 21-gun salute and ceremonial state dinner, in a symbolic statement that will let him show the Chinese people that he and his country are being treated as a great power. But US officials admit the litany of problems now plaguing US-China relations and doubts over Xi's commitment to a "peaceful rise" are unlikely to be resolved over butter-poached Maine lobster or grilled cannon of Colorado lamb. "Far and away, the most constructive engagements they've had have been in their private dinners," said senior Obama national security aide Ben Rhodes.