U.S. Secretary of State Antony Blinken has arrived in Kyiv for a one-day visit carrying an anti-corruption message as Washington shows its strong backing for the country in the face of heightened tensions with Russia.

Blinken said on Twitter on May 5 that the visit “will be an important opportunity to discuss continued Russian aggression and to underscore the need for maintaining both the pace of and focus on reforms with our Ukrainian partners.”

The top American diplomat is to meet with President Volodymyr Zelenskiy, Foreign Minister Dmytro Kuleba, members of Ukraine’s parliament, and civic leaders, on May 6.

Zelenskiy has said he wants to hear strong signals from the United States supporting Ukraine’s desire to join the NATO military alliance.

A statement issued on May 5 by the U.S. State Department on the strategic partnership between Kyiv and Washington does not mention Ukraine’s NATO aspirations, but says the United States continues to monitor the situation regarding “Russia’s ongoing aggressive actions and rhetoric targeting Ukraine.”

Ukraine is also expected to push for more military aid from the United States.

The statement notes that since 2014, the United States has provided Ukraine more than $4.6 billion in total assistance.

The statement also reiterates the U.S. position that Donbas and Crimea are part of Ukraine and calls on Russia to return full control of the peninsula to Ukraine and work in good faith to end the conflict in eastern Ukraine.

Blinken’s visit is intended to demonstrate America’s “unwavering” support as Ukraine copes with Russia’s backing of separatists in eastern Ukraine and a recent buildup of troops along its border.

But U.S. concerns about corruption are also on the agenda, notably in Ukraine’s energy sector.

State Department spokesman Ned Price this week slammed the move to replace the board of Ukraine’s state-owned oil and gas company Naftogaz, saying it “reflects a disregard for fair and transparent corporate governance practices and complicates long-standing efforts to reform Ukraine’s energy sector and improve its investment climate.”

The government on April 28 announced the dismissal of Andriy Kobolyev, Naftogaz’s chief since 2014, citing the “unsatisfactory” results of the company’s operations last year, when it posted a loss of nearly $700 million.

The supervisory board, which was temporarily suspended in order to dismiss Kobolyev, issued a statement on April 30 saying that all its members were submitting notice of their resignations, effective from May 14.

With reporting by AP