China's President Hu Jintao, center, with Secretary-General of Vietnam's Communist Party Nong Duc Manh, right, and Vietnam's President Tran Duc Luong, left, at Vietnam Communist Party headquarters in Hanoi

Chinese President Hu Jintao is in the Vietnamese capital for talks expected to focus on trade and possible military cooperation. The two communist-ruled countries have grown closer in past years as they reform their economies to compete on the global stage.

The sounds of the Chinese national anthem being played in Hanoi would have been unthinkable just a few decades ago. But as Chinese President Hu Jintao began a three-day state visit Monday, it was clear that the one-time enemies have entered a new era of cooperation.

Mr. Hu, also China's Communist Party chairman, took a stroll through cheering crowds of well-wishers near Vietnam's Communist headquarters. He was accompanied by the Vietnamese party's general secretary, Nong Duc Manh, and by President Tran Duc Luong.

The warm ceremony was a far cry from the historically tense relations between Vietnam and China. Vietnam spent nearly a millennium fighting off Chinese invasions, and most recently won a brief border war with Beijing in 1979. But since the end of the Cold War, Hanoi's leaders have been drawing closer to their communist brethren to the north.

Mr. Hu is expected to discuss closer military cooperation between the two countries. Yet at the same time, Vietnam has also been drawing closer to another former enemy - the United States. Earlier this year, Vietnam's prime minister visited the United States and agreed to future exchanges of military officers.

Carl Thayer, a Vietnam expert at the Australian Defense Academy, says Hanoi is trying to use the United States as a counterbalance to China's military might, while keeping friendly with both powers.

"As Vietnam has held its breath and increased military cooperation with the United States, it is now doing the same thing with China, so it has positioned itself well," said Mr. Thayer.

Hanoi may be wary of its giant neighbor's growing military might, but their communist ideology gives the two countries much in common. Mr. Thayer says Vietnam is especially keen to learn from China's experiences with market reform.

"In the last 10 years specifically, there has been a pattern of high-level party delegations that have studied intensively the Chinese experience," he continued. "But Vietnam is never slavish, because China has enormous environmental problems, domestic unrest in the urban areas, [and] imbalance in investment between coastal and inland regions, and Vietnam is trying very hard to counteract all that. So it has learned from China directly, but it has picked up the bad lessons of China and tried not to repeat them."

Mr. Hu is scheduled to address Vietnam's National Assembly on Tuesday and will fly Wednesday to the central city of Danang before heading home to Beijing.