European Union High Representative for Foreign Affairs Federica Mogherini and Iranian Foreign Minister Javad Zarif. Photo: The U.S. Department of State.

One of the last major outstanding issues confronting negotiators attempting to finalize a nuclear deal this week is the U.N. arms embargo against Iran, Bloomberg reported on Wednesday.

Russia Foreign Minister Sergei Lavrov said the U.N. ban “was the only major sticking point on the sanctions relief Iran demands as the price of a nuclear pact,” according to the report.

According to Bloomberg, Russia defense industries stand to make $7 billion in arms sales over the next decade, should these sanctions be lifted.

Defense Secretary Ashton Carter said, “We have serious concerns with Iranian malign activities outside of the nuclear issue.”

He said defense officials wanted to make sure Iran’s military remained isolated and hindered from greatly upgrading its “equipment and material.”

But Russia believes Iran is in need of a “huge upgrade” of its fighter jets, navy, and air defenses, according to the report.

Gary Sick, a former National Security adviser under three U.S. presidents, even went as far as to say “It’s not the U.S. negotiating with Iran. I think we’re negotiating with the Russians.”

Iran has said it wants the arms embargo lifted because it believes it to be “extraneous” to the nuclear issue, according to the report.

Critics of the deal, including Israel and many in Congress who will be able to review and approve the final deal, believe Iran will use unfrozen funds to boost its military and expand its influence throughout the Middle East, where its proxies already pose threats to stability in Yemen, Syria, Iraq and the Palestinian controlled territories.

Sen. Robert Menendez, the chair of the Senate Foreign Relations Committee, meanwhile told CNN that “A good bad deal is the essence of where we’re headed here.”

Menendez said Congress’ approval of the deal is far from decided, but he said the Senate would likely have enough votes to kill the agreement if a “bad deal is accepted.”

Negotiators from Iran, the U.S., U.K., Russia, China and Germany on Wednesday entered the 12 day of negotiations in Vienna, busting through two self-imposed deadlines. Administration officials took an optimistic tone saying negotiators have “have never been closer” to a comprehensive agreement, according to the Wall Street Journal.