Maryland U.S. Sen. Ben Cardin assumed the chairmanship of the Senate Foreign Relations Committee on Wednesday, stressing human rights and calling the defense of Ukraine “by far the highest priority.”

“Making sure that Russia does not succeed in Ukraine is in the U.S. national security interest,” the Democrat told reporters Thursday, one day after officially becoming chairman.

“China is watching, we know that,” Cardin said. “North Korea is watching, Iran is watching. And right now we’re making progress in preventing those countries from taking military action or aggressive action because they see the resolve in the United States and their coalition partners.”

Cardin, 79, a Democrat who announced in May that he will not seek reelection in 2024, replaces New Jersey Sen. Bob Menendez, who was indicted last Friday on federal charges that he accepted bribes in return for using his position to aid several businessmen and the government of Egypt.

The Foreign Relations Committee plays a significant role on a range of international issues, including policy toward China, and support for Ukraine in its defense against Russia.

Cardin, who has long emphasized foreign relations, lists among his top achievements a 2016 law he championed with John McCain, the late Republican senator from Arizona, to allow the United States to sanction foreign officials who commit human rights violations and ban them from entering the country.

As chairman, he said his priority “is to make sure that our foreign policy is wrapped in our values, in democracy, human rights, anti-corruption, transparency and accountability. That’s America’s strength.”

Fellow Maryland Democratic Sen. Chris Van Hollen is also on the committee. Idaho Sen. Jim Risch is the panel’s top Republican, and Cardin emphasized Thursday that he hoped to work closely with Risch.

In 2015, Cardin replaced Menendez as the committee’s Democratic leader after the New Jersey politician was indicted on federal bribery and conspiracy charges. That case ended with a deadlocked jury in 2017, and Menendez returned to the panel.

Cardin said last spring that he won’t seek reelection next year, ending a nearly six-decade run in Maryland politics.