President Donald Trump signed a Russia sanctions bill Congress imposed on him, adding a statement informing that the administration will carry out the law but with reservations about its impact and the constitutionality of some provisions.

In a statement that accompanied the notice that he signed the legislation into law, Trump laid out a list of concerns, saying it hindering the presidential authority, and it may damage the U.S. ability to work with allies and that it could have unintended consequences for American companies.

“While I favor tough measures to punish and deter aggressive and destabilizing behavior by Iran, North Korea, and Russia, this legislation is significantly flawed,” the statement released by the White House said.

The president points that his administration is determined to carry out the law in a way consistent with his constitutional authority, language that leaves open some room for interpretation of how the law is executed.  Trump’s concerns cover four areas:

encroachment on executive authority, unintentional harm to U.S. companies and business, as well as U.S. international partners, and limits on the flexibility of the administration to act in concert with allies in dealing with Russia.

The legislation, passed by overwhelming, veto-proof margins in the U.S. House and Senate, strengthens sanctions on Russia and gives Congress the power to block the president from lifting them. The bill also imposes new sanctions on Iran and North Korea.

White House officials had argued that it hampered the president’s ability to negotiate. In a separate statement announcing he signed the bill, Trump asserted he had unique ability in that area.

“I built a truly great company worth many billions of dollars,” he said in the statement. “That is a big part of the reason I was elected. As president, I can make far better deals with foreign countries than Congress.”

The legislation cleared both the House and Senate by wide margins, indicating any presidential veto would be overridden. Signing statements aren’t a new phenomenon, but their use has increased in the modern era. Obama and George W. Bush used signing statements to express displeasure or signal planned modifications to legislation they felt compelled to sign over their own objections.