President Bush, in signing the defense policy bill Tuesday, issued a statement indicating he reserves the right to heed or disregard four of its provisions as he sees fit.

Bush’s issuance of so-called signing statements has become a signature move of his presidency. The statements typically assert the limits of Congress’s power over the executive branch.

Every president since Ronald Reagan has repeatedly engaged in the practice, but none as frequently as Bush, who has objected to more than 1,000 provisions of laws he has enacted, according to a 2007 Congressional Research Service report.

The provisions at issue in the defense bill “purport to impose requirements that could inhibit the president’s ability to carry out his constitutional obligations to take care that the laws be faithfully executed, to protect national security, to conduct diplomatic negotiations, to supervise the executive branch, to appoint officers of the United States, and to execute his authority as commander in chief,” the White House statement said.

The disputed parts of the $611 billion bill include a ban on the use of U.S. funds authorized in the measure “to exercise control of the oil resources of Iraq.”

Bush also questioned the validity of a requirement in the bill that the U.S. government initiate negotiations with Baghdad on an agreement to share costs of combined military operations in the Iraq war zone.

Also covered by Bush’s statement was a provision providing certain personnel authorities to a Wartime Contracting Commission and another that would create in the Pentagon an office called the director of Operational Energy Plans and Programs.

“The executive branch shall continue to construe such provisions in a manner consistent with the constitutional authority and obligations of the president,” the White House statement said.