Iran’s foreign minister, Mohammad Javad Zarif, said Wednesday that President Barack Obama was “responsible” for making sure that Washington respects a final agreement over Iran’s nuclear program, even though Congress has been given a say on the accord’s fate.

“It is the obligation of the government of the United States to implement its international agreements. And we will hold the U.S. government, the U.S. president accountable” for the application of the treaties that they sign, Zarif told journalists in Lisbon, according to the AFP news agency.

He was speaking a day after the Senate Foreign Relations committee gave the green light to a bill that would give Congress the right to review a possible final agreement on the Iranian nuclear issue.

Zarif, who is also Iran’s chief nuclear negotiator, said Iran would study the bill “to see if it infringes upon or hinders the capability of the president to carry out the obligations that he is going to assume with Iran.”

The bill would mandate that the administration send the text of a final accord, along with classified material, to Congress as soon as it is completed. It also halts any lifting of sanctions during a congressional review and culminates in a possible vote to allow or forbid the lifting of congressionally imposed sanctions in exchange for the dismantling of much of Iran’s nuclear infrastructure.

Global powers reached a framework agreement for a deal with Iran on April 2. They must now resolve a series of technical issues by a June 30 deadline for a final deal, including the steps for lifting sanctions on Iran, and remaining questions over the possible military dimensions of its nuclear program.

Iran wants sanctions lifted immediately the deal is signed, while the powers are saying they will be eased gradually, and want a mechanism to ensure they can be swiftly re-imposed if Iran breaks its word.

Zarif also said Wednesday that Russia’s decision to go ahead with the sale of S-300 air defense missile systems to his country is “fully legal” and has no impact on the talks for a nuclear deal with major powers.

“Russia is fulfilling its contractual treaty obligation to deliver the S-300 defense capabilities to Iran. It had nothing to do with the negotiations,” he said, according to AFP.

“I think it is the right decision that Russia has made, it is a contract that we have with Russia which is fully legal and will have no impact on the negotiations,” he added.