BP has said repeatedly that it will pay for the disastrous oil spill in the Gulf of Mexico. But its actions show that it does not intend to go it alone.

Newly released documents show that on June 2, BP sent out demands for nearly $400 million to its partners in the well, the Anadarko Petroleum Corporation and the Mitsui Oil Exploration Company of Japan, or roughly 40 percent of the $1 billion BP spent in May.

The amounts demanded by BP  $272 million from Anadarko and $111 million from Mitsui  reflect the provisions of each company’s joint operating agreement with BP, which gives a share of liability equal to each company’s share of ownership.

BP owns 65 percent of the well, Anadarko owns 25 percent, and Mitsui 10 percent. The bills include costs of drilling the relief wells, responding to the spill and the reimbursements already sent to the federal government, as well as the claims BP has already paid for economic loss to people along the Gulf Coast.