Several US lawmakers criticized China Friday for its "deeply troubling" actions in disputed areas of the South China Sea, and urged passage of legislation that seeks peaceful solutions to rising maritime tensions.
Communist neighbors China and Vietnam have seen tensions soar since Beijing announced last week it would move a drilling rig into contested waters.
Several collisions in the area have been recorded between Chinese and Vietnamese ships, with each side blaming the other for the incidents.
"China's recent movement of an oil drilling rig escorted by military and other ships into disputed waters in the South China Sea off the coast of Vietnam -- and the subsequent aggressive tactics used by Chinese ships, including the ramming of Vietnamese ships -- is deeply troubling," the senators said in a statement.
"These actions threaten the free flow of global commerce in a vital region."
The bipartisan group of six lawmakers, led by Senate Foreign Relations Committee chairman Robert Menendez, are sponsors of a non-binding resolution introduced in April that condemns the use of force and advocates a peaceful diplomatic resolution of territorial and maritime claims.
China and Vietnam, which fought a brief border war in 1979, have been locked in a longstanding territorial dispute over the waters and related oil exploration, fishing rights and sovereignty in the Spratly and Paracel Islands.
But Beijing is also locking horns with other Asian nations that have competing claims in the South China Sea, including the Philippines and Malaysia, as well as with Japan in a separate territorial dispute.
In November China set up an "air defense identification zone" (ADIZ) over the East China Sea that included contested islands claimed by it and Tokyo, prompting condemnation by Washington.
The senators warned that the ADIZ and Beijing's "harassment of Japanese vessels around Japanese-administered territory in the East China Sea all raise serious questions about China's approach to regional security."
Earlier Friday Beijing defended itself against previous "irresponsible" US criticism about the escalating dispute with Vietnam.
US Assistant Secretary of State Daniel Russel was in Hanoi Wednesday where he told reporters that Washington opposed "any act of intimidation" in disputed areas and hoped sovereignty issues could be settled diplomatically.