BEIJING - China and Russia condemned U.S. missile-defense plans yesterday, taking a harder common line during Dmitry A. Medvedev's first foreign trip as Russian president.

Pushing forward their robust energy cooperation, Russia also signed a $1 billion deal to build a uranium-enrichment facility in China and supply low-enriched uranium for use in China's nuclear-power industry over the next decade.

Rivals throughout much of the Cold War, Moscow and Beijing have forged close political and military ties since the Soviet collapse, seeking to counter the perceived U.S. global domination.

They have spoken against the U.S. missile-defense plans in the past, but yesterday's declaration by Medvedev and Chinese President Hu Jintao sounded tougher than before.

Without naming the United States, the two leaders said that "the creation of global missile-defense systems and their deployment in some regions of the world . . . does not help to maintain strategic balance and stability and hampers international efforts in arms control and nuclear nonproliferation."

The joint position appears to raise the stakes for Washington, which has been trying to persuade Beijing and Moscow not to see the missile shields as threatening. At the same time, the cooperation on diplomatic issues masks deep Russian unease at China's growing power and differences over military and energy sales.

"We're going to work with them to work through these concerns, and we think we can resolve any concerns that anyone has about this and the true nature of the program," White House spokesman Tony Fratto said.

Beijing has criticized U.S. plans for antimissile defenses with Japan and Taiwan in the past, fearing that it would blunt China's large arsenal of missiles.

But Beijing has mostly been content to let Russia take the lead publicly, knowing the planned deployment of missile defense sites in Poland and the Czech Republic touch a core Russian interest.

"I think that now Russia has convinced China that it needs to speak out more clearly and take a position," said Fyodor Lukyanov, editor of Russia in Global Affairs magazine.

Statements of cooperation and support aside, there are friction and uncertainty over energy and the nations' shifting economic and diplomatic fortunes. While Moscow and Beijing have pooled efforts in keeping the West out of Central Asia, they are rivals for control of the region's riches.

Medvedev's stop in Kazakhstan on his way to China apparently was intended to send a message to Beijing and the West that Moscow continues to see the former Soviet Central Asia as its home turf.