The White House said on Tuesday it remains committed to nuclear negotiations with Iran despite Tehran's "provocative" statement that it will ramp up uranium enrichment.
"We are certainly concerned about these provocative announcements," White House Press Secretary Jen Psaki told reporters, according to AFP.
"We believe that the diplomatic path is the only path forward here and that having a discussion, even indirect, is the best way to come to a resolution," she added.
Her comments came hours after Iranian negotiator Abbas Araghchi announced that Iran would begin enriching uranium to 60% purity, its highest level to date in response to the blackout and explosion which occurred at the Natanz nuclear facility over the weekend.
The move would shorten Iran's breakout time to being able to construct a nuclear weapon.
The announcement has cast a shadow over attempts by Washington to negotiate a renewal of the 2015 nuclear deal.
Biden has indicated a desire to return to the deal, and indirect talks between Washington and Tehran started last week in Vienna. Psaki said Tuesday she expects them to continue.
The six countries that negotiated the JCPOA with Iran should be "unified in rejecting" Iran's threat to accelerate uranium enrichment, Psaki said.
However, it "underscores the imperative of returning to mutual compliance with the JCPOA," she added, calling talks last week "constructive."
"While (talks) were difficult and while we expect this to be long, we expect and we have not been alerted of any change in planned attendance in meetings that will resume later this week," said Psaki.