"The risks of a mishap in the region were highlighted last month when the guided missile cruiser USS Cowpens had to take evasive action to avoid hitting a Chinese warship operating in support of Beijing's first aircraft carrier, the Liaoning.
"Locklear said the incident had prompted a US demarche - a formal diplomatic statement of concern - to Beijing
"China believed it issued notification to maritime traffic to steer clear of the Liaoning, [Admiral Samuel] Locklear[, the head of the US military's Pacific Command,] said. But he added that the Cowpens, which was monitoring the carrier, had no such notice.
"Locklear has attributed the incident to the Chinese navy's inexperience with deployments in international waters around other warships, one reason the US officials are looking forward to China's participation in the US military's multinational RIMPAC naval exercises near Hawaii this year.
(b) There is no need to read the rest of the Reuters report, which one can imagine. What is interesting is US position on USS Cowpens, which suggests that US, much less Cowpens, was unaware of, or did not receive, China's notification (if notification was indeed made).
(c) démarche (n; French démarche, literally, gait, from Middle French, from demarcher to march, from Old French demarchier, from de- + marchier to march):
"a petition or protest presented through diplomatic channels" www.merriam-webster.com/dictionary/démarche
(d)
(i) The English surname Locklear: "Probably a variant of English Lockyer"
(ii) The English surname Lockyer: "a locksmith"
(e) 美军指挥官促设美中军事热线. VOA Chinese, Jan 23, 2014 www.voachinese.com/content/us-commander-20140123/1836365.html
(“美军太平洋司令部司令洛克利尔1月23号在五角大楼与媒体见面的时候表示“)
This explains the occasion. There is no need to read the rest of the VOA report.