Her departure, which is expected to take effect in the coming weeks, creates a vacancy as the Trump administration faces major new threats and challenges specifically related to arms control.
Iran recently threatened to resume production of nuclear centrifuges in response to President Trump’s decision last year to withdraw from the 2015 Iran nuclear deal and reimpose economic sanctions. Trump has also ordered his top aides to make a new push for a historic trilateral arms control agreement involving Russia and China, something Beijing has long dismissed.
During her tenure, Poblete clashed with her boss, Undersecretary of State Andrea Thompson, Vice President Pence’s former national security adviser, said the officials and aides familiar with the infighting.
In particular, disagreements surfaced over the State Department’s report on international compliance with arms control accords, the people said.
“The tension over the compliance report has been very real, and [Thompson’s office] is now demanding sign-off much earlier in the clearance process,” said one State Department official, who like others spoke on the condition of anonymity to discuss personnel moves.
In April, Reuters reported that some U.S. officials were concerned that the compliance report politicized and slanted assessments about Iran, which the Trump administration has singled out as the country’s principal foe.
Poblete, whose views on arms control were more aligned with national security adviser John Bolton rather than Thompson’s, previously served as the chief of staff of the House Foreign Affairs Committee among other jobs.
As her confirmation process for the senior arms control job dragged on, White House press secretary Sarah Sanders excoriated Democrats and emphasized the importance of the position.
“It has been almost 150 days since Dr. Poblete was nominated,” Sanders said. “Senator Schumer is holding her up, putting the safety and security of the American people and, frankly, the entire world in danger.”
Poblete was a favorite among hard-line anti-Iran groups such as the Foundation for Defense of Democracies, which hosted her for a speech in July 2018 in which Poblete praised the U.S. withdrawal from the Iran deal.
“The JCPOA was flawed at both the technical and political levels, and at the practical level,” she said in the speech, referring to the acronym for the 2015 deal.
Nonproliferation experts who supported the Iran deal viewed her departure with ambivalence.
“While the State Department can hardly afford to lose another senior leader, it is not clear that Assistant Secretary Poblete was contributing to the advancement of arms control in a helpful or substantive way,” said Alexandra Bell, senior policy director at the Center for Arms Control and nonproliferation and a former Obama administration official. “The recent debacle involving the sloppy and politically charged summary of the unclassified 2019 Compliance Report is an example of that.”
“The Trump administration should immediately move to appoint a qualified, seasoned expert to the position,” she added.
Anne Gearan contributed to this report.