US Defense Secretary Lloyd Austin and Ukrainian Defence Minister Andriy Taran walk past honor guards during a welcoming ceremony before their meeting in Kiev on October 19, 2021.
CNN  — 

US Defense Secretary Lloyd Austin on Tuesday called on Russia to stop its occupation of Crimea and to halt its “persistent cyberattacks” against the United States.

“We again call on Russia to end its occupation of Crimea, to stop perpetuating the war in Eastern Ukraine, to end its destabilizing activities in the Black Sea and along Ukraine’s borders,” Austin said during a press conference in Kiev, Ukraine, alongside his Ukrainian counterpart Andrii Taran.

“And to halt its persistent cyberattacks and other malign activities against the United States and our allies and partners,” he added.

Austin’s visit to Ukraine is his second stop in Europe this week “to reassure allies and partners of America’s commitment to their sovereignty in the face of Russian aggression,” according to the Pentagon. The US defense secretary on Monday visited Georgia, where Russia still occupies roughly 20% of the nation, and plans to visit Romania, ahead of attending the NATO Defense Ministerial in Brussels.

The White House last week called on Russia to take further action against ransomware groups operating from the country, but acknowledged that Moscow has taken “some steps” after President Joe Biden urged Russian President Vladimir Putin to tackle the groups in the summer.

Biden in June urged Putin to crack down on Russian-speaking hackers after a recent string of ransomware attacks crippled critical infrastructure and business operations, like the attack against Colonial Pipeline in May. Russian hackers were also deemed to be behind last year’s massive breach of several US federal agencies by exploiting software made by SolarWinds.

Earlier this year, Russian troops had amassed the largest buildup of troops near the Ukrainian border since 2014, when Russia annexed Crimea from Kiev. Russia, however, pulled back from a confrontation, returning troops to their bases after taking part in exercises near the Ukraine border.

As the US steps up its support to the neighbors of Russia that are on the “frontlines of Russian aggression,” Russia announced Monday it is suspending its permanent mission to NATO.

Russia’s Foreign Minister Sergey Lavrov said the move was in response to the alliance’s expulsion of eight Russians earlier this month.

On Tuesday, Austin stressed that the US’ support for Ukraine sovereignty is “unwavering” and “we will continue to do everything we can to support Ukraine’s efforts to develop the capability to defend itself.”

Asked about Russia’s opposition to Ukraine’s accession to NATO, Austin argued that Ukraine “has a right to decide its own future foreign policy and we expect that they will be able to do that without any outside interference.”

“No third country has a veto over NATO’s membership decisions,” he said.

CNN’s Stephanie Halasz contributed to this report.