Vietnamese protesters hold placard with an image of the late captain Nguy Van Tha who was killed in the battle of the Paracel Islands, during a march at the King Ly Thai To garden to mark the 40th anniversary of the deadly naval battle between China and South Vietnam, in Hanoi, Vietnam, Sunday. Pic: AP.

HANOI, Vietnam (AP) — Around 100 anti-China protesters shouted slogans and carried banners in Vietnam’s capital on Sunday to mark the 40th anniversary of a deadly naval battle between China and South Vietnam.

Police broke up the protest in Hanoi after around half an hour, but made no arrests.

Protests are extremely rare in communist Vietnam and are typically quashed quickly by security forces. Dissidents and others accuse the government of not being tough enough against Beijing and its increasing assertiveness in pressing claims in the South China Sea.

The 1974 naval battle, in which 74 South Vietnamese soldiers died, followed China’s occupation of the Paracel islands. It is especially sensitive because the North Vietnamese government didn’t counter the Chinese move, or even acknowledge force was used. At the time, Beijing was giving North Vietnam arms and money to fight the U.S. and South Vietnam.