On Sunday, Iran announced that it would be breaching another limit set by the 2015 international accord placing restrictions on its nuclear programs. The nation announced it would be enriching uranium beyond the 3.67% purity limits outlined in the deal, another (small) escalation of its nuclear enrichment efforts after the Trump administration unilaterally withdrew the United States from the accord and imposed severe new sanctions. It follows an intentional Iranian breach of nuclear stockpile limitations announced last month.
Trump's sudden withdrawal from the multilateral nuclear deal has created turmoil as his administration insists both that other nations abide by United States-crafted sanctions against Iran but that Iran itself continue to adhere to nuclear restrictions. This new move by Iran is overtly intended to put pressure on the United States and on remaining signatories to the 2015 accord: The New York Times reports that Deputy Foreign Minister Abbas Araghchi declared that Iran would commit additional breaches of the nuclear deal in "60-day intervals" unless other international signatories provide relief from Trump-imposed sanctions. (The Trump administration, in the meantime, has been threatening severe punishment for allies that do not go along with their new sanctions protocol regardless of prior Iran agreements.)
Iran, then, is attempting to force the issue by obliging European allies of the United States to either ignore U.S. sanction demands or scrap the nuclear deal entirely. Each breach of the nuclear accord makes only small changes to Iran's actual nuclear capabilities; the regime is taking a series of small steps solely for diplomatic, rather than scientific, effect.
There is no question that Trump's imposed sanctions have severely affected Iran's economy and citizens—as intended by Trump's always-maximalist foreign policy hangers-on. But the United States has not gone uninjured itself; it finds itself in a position where longtime U.S. allies are now deeply skeptical of American policy tactics and objectives, to the point where an Iranian theocracy cannot simply be brushed off as the more unreasonable opponent.
That diplomatic weakness is likely a major cause of the rising administration appetite for turning the conflict between the two nations into a military exchange, rather than a diplomatic one. The Trump administration had presumed Iran would bow to new demands fairly quickly. When Iran did not (the American neoconservative foreign policy establishment has a history of being caught flat-footed after belligerent policy actions result in outcomes other than the quick victories they predicted, and that is putting it lightly), Trump's advisers quickly ran out of other ideas.