Mr Aso, the first foreign leader to visit the US president since his inauguration, was also set to announce the appointment of a special envoy to co-ordinate support for US efforts to rebuild the war-torn country, the prime minister's spokesman said shortly before the summit.
Washington will welcome the police funding, which comes as the US asks Nato allies in Europe for more money to expand the Afghan army. The Pentagon wants to increase the Afghan army to 134,000 troops by 2012 at an expected cost of $17bn.
With Mr Aso's opinion poll ratings slumping and sections of his ruling Liberal Democratic party in open revolt, US officials have stressed that the decision to invite him to Washington was intended as an honour for his office rather than its incumbent.