The Kremlin lifted its self-imposed ban on the delivery of a powerful missile air-defense system to Iran on Monday, stoking sharp criticism from the White House and Israel and casting fresh doubt on the international effort to curb Tehran’s nuclear program.

U.S. lawmakers seized on Moscow’s announcement Monday to warn Russia was among a host of foreign countries using the prospect of a nuclear deal to begin seeking out lucrative business deals that could bolster Iran’s military and economy.

Any delivery of an air-defense system would complicate airstrikes on Iranian nuclear facilities by Israel or the U.S. should the diplomatic track fail.

Iran thinks that Russia will deliver the missile system this year, Ali Shamkhani, secretary of Iran’s Supreme National Security Council, told the Interfax news agency in Moscow on Tuesday.

The U.S. Senate is set to vote this week on legislation that would provide Congress with the power to approve, amend or kill any agreement that seeks to curb Iran’s nuclear program in exchange for a lifting of international sanctions.