Secretary of Defense Lloyd Austin is travelling to Europe to reassure allies and partners of America’s commitment to their sovereignty in the face of Russian aggression, the US Department of Defense said on Sunday.

Secretary Austin will visit Georgia, Ukraine, and Romania before attending the NATO Defense Ministerial in Brussels.

“We are reassuring and reinforcing the sovereignty of countries that are on the frontlines of Russian aggression,” said a senior defense official.

Austin will stress in both Georgia and Ukraine that there is an open door to NATO and encourage the nations to make the changes necessary for them to qualify for membership in the defensive alliance, the statement read.

Austin is also going to recognize the nations for their support. “In terms of sacrifices, it is important to note that Georgia … was the top, per capita contributor to the Resolute Support Mission in Afghanistan, and suffered many losses from that mission,” the official said.

All three countries border the Black Sea, and Austin will speak to their leaders about Black Sea security and seek to strengthen cooperation among these nations, the statement read.