Iran reportedly fired two ballistic missiles this weekend, the first alleged ballistic missile test since the Trump administration put the Islamic Republic “on notice” a month ago. On Thursday morning, an Iranian official said the projectile was a Hormuz-2 anti-ship ballistic missile (ASBM). A return to ballistic missile testing, whether covert or overt, signals Tehran intends to test the Trump administration’s limits, just as it did with its predecessor.

On February 3, Treasury designated 25 entities and individuals for links to Iran’s ballistic missile activities and supporting terrorism. Since then, Tehran has engaged in four military drills, opting to test rockets, surfacetoair and anti-tank missiles, and a torpedo. Iran also claimed to have tested a cruise missile called the Nasir, which it later boasted was submarine-launched.

Both missiles tested this weekend were reportedly a variant of the short-range single-stage solid-fueled Fateh-110 class dubbed the Fateh-110 Mod-3. According to unnamed U.S. officials cited by Fox News, which broke the story of the test, the missiles carried an “active seeker,” thus letting it target moving vessels. Yet it remains to be seen if this guidance system was operational, as Iran’s first launch reportedly failed to make contact with its target, and the missiles were fired at a barge that may not have been moving at all.

Iran’s existing stock of ASBMs includes the Khalij-e Fars, and the Hormuz 1 and 2 – all of which are based on the Fateh-110 and share a comparable design and flight profile. Iran has also used the Fateh-110 as a baseline to develop the Fateh-313 and Zulfiqar, both of which were intended to improve the range, payload, and accuracy of Iran’s arsenal of surface-to-surface short-range ballistic missiles.

Since agreeing to the nuclear deal in July 2015, Iran has launched as many as 14 ballistic missiles with little reproach from Washington and the international community. Former UN Secretary General Ban Ki-moon decried these tests last year as contrary to “the constructive spirit” of the accord, but deferred to the UN Security Council “to interpret its own resolutions.”

Iran has its reasons to engage in such destabilizing behavior. Flight tests provide the Islamic Revolutionary Guard Corps’ Aerospace Force – which oversees Iran’s ballistic missiles – with crucial data about the readiness and reliability of its arsenal. But missile launches also have another function: bolstering Iranian deterrence, a key component of the country’s foreign and security policy.

To that effect, Supreme Leader Ali Khamenei said Monday, “To discourage the enemy from attacking, we must avoid expressing weakness and make evident the many strengths we possess.” Occasional missile tests appear to be the way in which the Islamic Republic reveals these aptitudes, incrementally flexing its muscles while daring its adversaries to respond.

Iran’s month-long decision to forgo ballistic missile launches – particularly as it conducted military exercises that often accompany such launches – likely indicated a cognizance of American red lines. Tehran seems to have decided it would still respond to U.S. sanctions with limited military drills, but not in a way that would trigger harsh punitive measures. While testing an ASBM does not communicate the same defiance as a medium-range ballistic missile, the Hormuz-2 launches nonetheless signal Tehran’s willingness to enter an escalatory spiral with Washington. As the Trump administration proceeds towards its 100-day mark, it must remember that Iran is closely watching how it responds to such military provocations.

Behnam Ben Taleblu is a senior Iran analyst at the Foundation for Defense of Democracies.