Secretary of State Mike Pompeo issued a statement Wednesday saying the US "rejects Russia's attempted annexation of Crimea and pledges to maintain this policy until Ukraine's territorial integrity is restored."
"The United States calls on Russia to respect the principles to which it has long claimed to adhere and to end its occupation of Crimea," the statement reads.
Pompeo is also expected to state in congressional testimony Wednesday that the United States will never recognize Crimea as part of Russia, a European diplomat briefed by the State Department told CNN.
Pompeo's declaration comes after President Donald Trump had appeared to cast doubt on his administration's commitment to Ukraine's claims over the peninsula.
Asked by reporters on Air Force One at the end of June whether the United States would recognize Russia's claim on Crimea, Trump ambiguously responded: "We're going to have to see."
Trump has repeatedly blamed former President Barack Obama for permitting Russia to annex the region in 2014.
In an interview with the Australian Broadcasting Corp. on Tuesday, Pompeo said Trump had discussed the situation in Ukraine with Russian President Vladimir Putin during their summit in Helsinki and the two leaders "didn't find much place to agree there."
Pompeo is also expected to defend the administration's handling of Russia and the Trump-Putin summit by laying out what he says are a list of tough Trump administration responses to Russia and to field questions from lawmakers about what Trump and Putin discussed in their two-hour-plus meeting in Helsinki when he appears before the Senate Foreign Affairs Committee.