The news came out Monday that Iranian fast-attack craft had once again harassed US Navy ships in the Persian Gulf with unsafe and unprofessional behavior, forcing the USS Mahan to fire warning shots.

The incident, the first of its type reported this year, follows a significant increase in Iran's navy harassing US ships in 2016, the US Navy has told Business Insider.

Iran's ability to undermine the West, to harass their ships in international waters, and to look militarily strong while having weak conventional forces owes to Tehran' ;expert handling of the US diplomatically and militarily, according to Behnam Ben Taleblu, a senior Iran analyst at the Foundation for Defense of Democracies.

Although the US lists Iran as the No. 1 state sponsor of terror and has accordingly moved to sanction Iran over the past few decades, the actions have not been enough to deter Iran. According to Taleblu, "sanctions are an important step, but they’re not the only step."

In addition to sanctions, the US would benefit from a signaling its resolve against Iran, where the Obama administration has been seen as "phobic" in confronting them.

The US "need[s] to make sure our commanders and CENTCOM (the US command responsible for the Middle East region) have a free hand — not to go rogue — but so they do not feel politically encumbered to defend themselves, US vessels, and partners in the region," said Taleblu.

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Retired Navy Captain Lawrence Brennan, also an expert on international maritime law and the rules of engagement, told Business Insider the US Navy's response so far has been "measured and appropriate under the circumstances," but also noted that it was likely muted somewhat by concerns over Iran's nuclear program in an incident that "seems to be near the edge," of militarily actionable behavior.

Others say that the Navy has exercised too much restraint under a president striving to improve ties with Iran, and that may be actually encouraging Iran to act aggressively.

Former US Navy Commander Jeremy Vaughan stressed in an essay for the Washington Institute that the strategic goals of the Obama administration may have confined Navy commanders to more docile responses to Iranian aggression.

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According to Vaughan, even when Navy commanders have established the "threat triangle" (determining that a threat has the capability, opportunity, and intent to harm the US Navy), sailors have not responded with force in keeping with naval guidance.

A specific example comes from the January 2016 capture of US Navy sailors on a broken down boat by the Islamic Revolutionary Guard Corps' navy during which the boat captain said he had thought the following: "the Commander in Chief would not want me to start a war over a mistake, over a misunderstanding."

So while no direct decree from the president has hamstrung the Navy, the overall political climate deterred a more forceful action.

How Iran bosses around the much stronger US