The US government is sending its highest-level diplomatic visitor to Thailand since last year's military coup, although a return to democracy there remains a distant prospect. The top US envoy for East Asia, Daniel Russel, will hold talks with Thai officials tomorrow, days after the military-appointed legislature voted to ban ousted prime minister Yingluck Shinawatra from politics for five years. she is also facing criminal charges that carry a 10-year prison term. The accusations against Yingluck, which she denies, centre on her oversight of a costly rice-subsidy scheme promoted by the elected government she led before the military takeover last May. But it is widely seen as an attempt to cripple the political machine founded by Yingluck's brother, Thaksin Shinawatra, another ousted prime minister, and prevent its return to power. In response to the coup, the United States has suspended US$4.7 million in military assistance to its oldest Asian ally. It has been calling for quick elections and a resumption of civilian rule. A new constitution is being drafted first, and analysts do not expect elections before 2016. Still, Washington chooses its words carefully as it looks to sustain a 182-year-relationship with Thailand, which has traditionally served a hub for US government engagement in Southeast Asia. Russel, who is on a four-nation tour of the region, will meet in Bangkok tomorrow with political leaders "on all sides" and discuss the US concerns with the government, the State Department said. Spokeswoman Jen Psaki took note on Friday of the actions against Yingluck, and said it was up to Thais to determine the legitimacy of their political and judicial processes. But she added: "We believe that the impartial administration of justice and rule of law is essential for equitable governance and a just society." In a sign Washington does not want its strained ties with Bangkok to prevent deeper security ties with the wider region - or leave too deep a rift with the Thai military - the US is pressing ahead next month with annual multi-nation military exercises in Thailand, called Cobra Gold, albeit on a smaller scale than in past years. Thailand has faced political turmoil since Thaksin's overthrow in 2006. The latest coup and the military's squelching of dissent have ended escalating violence but risk deeper divisions between the pro-military elite and largely rural poor who strongly support Thaksin.