Facebook Inc and Google Alphabet Inc. agreed to cooperate and help each other if their agreement to work together on online advertising is investigated, the Wall Street Journal reported.

The publication provides an unedited version of the lawsuit filed by 10 states against Google last week. The US accused Google of illegally collaborating with Facebook in violation of antitrust laws to develop the already dominant online advertising business.

The lawsuit said Google and Facebook knew their agreement could trigger an antitrust investigation and were discussing how to deal with it.

A Google spokesperson told that such antitrust threat agreements are extremely common.