As much as the United States' new tone toward Iran is worrisome, and as much as the Islamic Republic's Jan. 29 ballistic missile test is disconcerting, Tehran and Washington are unlikely to collide directly.

In both capitals, decision-makers see an urgent need for harsh rhetoric — albeit for different reasons. The Iranians see a need to show resilience vis-a-vis an explicitly hostile US administration. Meanwhile, the latter wants to make clear to both its domestic and international audience that the Obama era is over. This involves signaling that the easing of tensions with Iran has ended. It also involves reassuring regional allies such as Saudi Arabia and Israel that Washington would not engage in a rapprochement with Tehran at their expense.

Indeed, it should not come as a surprise that US national security adviser Michael Flynn's warning that Iran "is officially on notice" came shortly after lengthy phone calls between the White House and both Israeli Prime Minister Benjamin Netanyahu and Saudi Arabia's King Salman bin Abdul-Aziz Al Saud.

But escalating rhetoric aside, the reality is that US policy toward Iran has largely remained intact.