UNITED NATIONS (Reuters) – Iran will likely escape new United Nations sanctions, though the U.N. Security Council could issue a public reprimand for recent launches of what Western officials described as ballistic missiles capable of carrying a nuclear warhead, diplomats said.

Council diplomats said the case for sanctions was weak, hinging on interpretation of ambiguous language in a resolution adopted by the 15-member body last July, part of an historic deal to curb Iran’s nuclear work.

International sanctions on Tehran were lifted in January under the nuclear deal brokered by Britain, France, Germany, China, Russia and the United States. Diplomats said all six countries agreed the ballistic missile tests do not violate the core agreement.

However, the Security Council resolution “calls upon” Iran to refrain for up to eight years from activity, including launches, related to ballistic missiles designed with the capability of delivering nuclear weapons.

Key powers agree that request is not legally binding and cannot be enforced under Chapter 7 of the U.N. Charter, which deals with sanctions and authorization of military force. But Western nations, which view the language as a ban, say there is a political obligation on Iran to comply.

Britain said the missile launches show Iran’s “blatant disregard” for the resolution, while France said it was “a case of non-compliance.” The United States initially deemed the tests a violation, but has softened that stance, calling Iran “in defiance” of the resolution.

Russia, which has Security Council veto power, says Iran has not violated the resolution. Russia opposes new U.N. sanctions, but acknowledged that if the missiles were proven capable of carrying a nuclear weapon, it could be suggested Tehran has not been “respectful” of the council.

“A call is different from a ban, so legally you cannot violate a call, you can comply with a call or you can ignore the call, but you cannot violate a call,” Russian U.N. Ambassador Vitaly Churkin said on Monday. “The legal distinction is there.”

Laura Rockwood, former chief of the legal department at the International Atomic Energy Agency and now head of the Vienna Center for Disarmament and Nonproliferation, said of the U.N. resolution: “This was probably a classic case of language negotiated with ‘constructive ambiguity’ in mind.”

In a 2010 resolution, the Security Council decided Iran “shall not” carry out activity related to ballistic missiles capable of delivering nuclear weapons – a clear, legal ban.

The United States agreed to soften the language on ballistic missiles in the July resolution, largely because Russia and China insisted, diplomats said.

“When you look at your hand, and you can’t even bluff … you fold,” said a U.S. official.

Despite Russia’s opposition to new sanctions, the United States has vowed to continue pushing for U.N. Security Council action on the ballistic missile tests. Instead of sanctions, the council could decide to issue a statement rebuking Iran, not only for the missile tests, but for threatening another state.

The commander of Iran’s Revolutionary Guards’ missile battery said the missiles tested were designed to be able to hit U.S. ally Israel. The United States condemned the remarks and Russia said countries should not threaten each other.

Churkin also argued the U.N. resolution required a heavy burden of proof that the ballistic missiles were “designed to be capable of delivering nuclear weapons.” The United States and its European allies are expected to make a technical case to the council about how Iran failed to abide by the U.N. resolution.

“These were designed to be capable of delivering nuclear weapons. This merits a council response,” U.S. Ambassador to the United Nations, Samantha Power, told reporters on Monday.

According to the International Missile Control Regime, ballistic missiles are considered nuclear capable if they have a range of at least 300 km and can carry a payload of up to 500 kg.

Mark Fitzpatrick of the International Institute for Strategic Studies said he did not believe Iran’s missile launches were a violation of the “ambiguous” resolution because the “missiles in question can’t be proven to have been designed to deliver nuclear weapons.”

Iranian officials, including pragmatist President Hassan Rouhani, insist Tehran’s missile program does not violate the nuclear deal or the U.N. resolution.

“With Russia and China on Iran’s side, there will be no resolutions, sanctions or any action against Iran over its missile or aerospace programs,” said a senior official in Tehran, speaking on condition of anonymity.

Now that sanctions on Tehran had been lifted, the official said Western countries were keen to do business in Iran.

“Iran is not being seen as a danger any more even for the Western countries,” the official said. “Iran is like a gold mine for them. They need us and we need them. So, why endanger this situation?”

(Additional reporting by Arshad Mohammed in Washington, Parisa Hafezi in Ankara and John Irish in Paris; Editing by David Gregorio)