"Iran confirms new missile test, says it does not violate nuclear deal"

UN Resolution 2231 section dealing with ballistic missiles found here. You need to look at paragraph 3 of Annex B, which reads in pertinent part:

3. Iran is called upon not to undertake any activity related to ballistic missiles designed to be capable of delivering nuclear weapons, including launches using such ballistic missile technology, until the date eight years after the JCPOA Adoption Day or until the date on which the IAEA submits a report confirming the Broader Conclusion, whichever is earlier.
4. All States may participate in and permit the activities described below provided that the Security Council decides in advance on a case-by-case basis
to permit such activity:
(a) the supply, sale or transfer directly or indirectly from their territories, or
by their nationals or using their flag vessels or aircraft to or from Iran, or
for the use in or benefit of Iran, and whether or not originating in their
territories, of all items, materials, equipment, goods and technology set
out in S/2015/546 and of any items, materials, equipment, goods and
technology that the State determines could contribute to the development
of nuclear weapon delivery systems; and
(b) the provision to Iran of any technology or technical assistance or
training, financial assistance, investment, brokering or other services,
and the transfer of financial resources or services, or Iran’s acquisition of
an interest in any commercial activity in another State, related to the
supply, sale, transfer, manufacture or use of the items, materials,
equipment, goods and technology described in subparagraph a of this
paragraph or related to the activities described in paragraph 3.

provided that in the event of an approval by the Security Council: (a) the contract for delivery of such items or assistance include appropriate end-user guarantees; and (b) Iran commit not to use such items for development of nuclear weapon delivery systems.(emphasis added)

Which the UN says means:

Paragraph 3 of Annex B of resolution 2231 (2015) calls upon Iran not to undertake any activity related to ballistic missiles designed to be capable of delivering nuclear weapons, including launches using such ballistic missile technology.

Effective to 2023 or maybe earlier.

So, with that as background, here's the Reuters report (from whence the post header), "Iran confirms new missile test, says it does not violate nuclear deal":

Iran's defense minister said on Wednesday it had tested a new missile but this did not breach the Islamic Republic's nuclear accord with world powers or a U.N. Security Council resolution endorsing the pact.

Iran has test-fired several ballistic missiles since the nuclear deal in 2015, but the latest test was the first during U.S. President Donald Trump's administration. Trump said in his election campaign that he would stop Iran's missile program.

"The recent test was in line with our plans and we will not allow foreigners to interfere in our defense affairs," Defence Minister Hossein Dehghan told Tasnim news agency. "The test did not violate the nuclear deal or (U.N.) Resolution 2231."

A U.S. official said on Monday that Iran test-launched a medium-range ballistic missile on Sunday and it exploded after traveling 630 miles (1,010 km).

The Security Council held an emergency meeting on Tuesday and recommended the matter of the missile testing be studied at committee level. The new U.S. ambassador to the United Nations, Nikki Haley, called the test "unacceptable".

Iranian Foreign Minister Mohammad Javad Zarif said on Tuesday that Tehran would never use its ballistic missiles to attack another country.

Hmmm. The question facing the UN is whether the missile that was fired was "nuclear capable" - if so, that's a clear violation of Resolution 2231, despite Iran's preemptive denial of that fact. Note that Resolution does not even come close to suggesting that "nuclear capability" refers somehow to the current capacity of Iran to load a nuclear warhead onto such missile. I would assert that if anyone - Russia, US, China, North Korea, Pakistan or others has a nuke that could fit the missile now or if Iran could, with or without the help of some other rogue state could develop that technology, Iran is in violation of the Resolution.

Which leads to question number 2, does Iran's assertion that its missile is, essentially, "for defensive purposes only" matter? No, that's not part of the Resolution as I read it.

Question 3: What can the UN or others do about this violation? Why, it's supposed to trigger a "snapback" of the sanctions lifted by the nuclear deal with Iran, according to this:

Under a council resolution that endorsed the historic nuclear deal with Iran, Tehran is barred from developing missiles designed to carry nuclear warheads.
Any violation of that resolution could trigger a snapback of sanctions that were lifted under the nuclear agreement, opening up the Iranian economy to investment and opportunities.

Now, who is going to move to reinstate the sanctions? And how do you enforce it?