The US company XpressWest announced unilaterally Wednesday to terminate its cooperation with China Railway International (CRI) in building a high-speed rail between Las Vegas and Los Angeles, in violation of the terms reached by the two sides. 

The CRI later responded that it is waiting for an explanation from XpressWest about its decision, which would mark the abrupt suspension of the project. 

In a press release issued Wednesday afternoon, XpressWest said it "has terminated its joint venture activities with CRI regarding high-speed passenger rail." 

A CRI manager responsible for the joint venture told Xinhua that XpressWest is precipitate and irresponsible to make such a statement while its talks with the CRI were still going on, vowing to spare no effort in defending CRI's interests. 

He added that the unilateral announcement also violated the cooperation framework agreement signed by the two sides, which stipulates that one side should not release related information without approval by the other. 

The past few months have brought a bumpy ride for bilateral negotiations between XpressWest and CRI since the two sides agreed in September 2015 to work together in building the high-speed rail. 

The CRI management said that XpressWest had kept adding new demands in the talks, some of which were unacceptable to the Chinese side.