A bipartisan group of U.S. senators expressed growing concern Friday about military cooperation between North Korea and Russia, saying it places new emphasis on the need for continued U.S. support for Ukraine.

In comments made separately to VOA’s Korean Service reporter Joeun Lee, the lawmakers said the North Korean-Russian cooperation could help both nations advance their military capabilities.

“I am concerned that North Korean artillery has come to Russia's aid at a critical time, and North Korean ballistic missiles are helping Russia carry out savage attacks on civilian centers across Ukraine,” said Democratic Senator Chris Coons of Delaware.

Republican Senator Pete Ricketts of Nebraska said the relationship between Russia and North Korea means additional U.S. funding for Ukraine — currently blocked in a budget and immigration debate between the House of Representatives and the White House — must be a priority.

“What we have to do is make sure that we're supporting our ally,” Ricketts said. He added that the U.S. must “make sure [Ukrainian troops] have got the weapons they need to be able to fight back.”

Senator Tim Kaine, a Democrat from Virginia, said the growing closeness of Russia and North Korea — as well as China and Iran — shows that the United States’ adversaries are learning the power of alliances.

“One of the strengths of the United States is alliances, and traditionally they have not used alliances the same way,” Kaine said. “But they're understanding that's a huge advantage for the U.S., and so anything they're doing together ... they're trying to create the lines because they haven't really had them.”

Democratic Senator Chris Van Hollen of Maryland echoed Ricketts’ sentiments, saying ongoing arms shipments from North Korea to Russia mean it’s time for the U.S. Congress to act.

“This is again why it's so important for the Congress to pass the supplemental appropriations and provide the people of Ukraine with military support they need to defend themselves,” Van Hollen said.