WASHINGTON (CNN) -- China has refused nine U.S. Navy ships and one Air Force jet entry to Hong Kong in the past month, U.S. military officials said Friday.





China has refused the USS Reuben James, seen in a 1989 photo, a Christmas port call in Hong Kong.





Senior Navy officials said that Beijing denied permission for the USS Reuben James, a Navy frigate, to make a holiday port call for sailors at the end of December.





The rejection occurred last week, at the same time China refused to allow the USS Kitty Hawk aircraft carrier battle group into Hong Kong for a Thanksgiving holiday port call.





A U.S. Air Force C-17 flight that had been scheduled for a routine resupply of the U.S. Consulate in Hong Kong also was denied permission to enter, Navy officials said.





The Kitty Hawk battle group was eventually granted permission to enter, but by then the ships were well on their way to port in Japan.





Days earlier, China refused to give two U.S. Navy minesweepers safe harbor in Hong Kong during a storm on the high seas.





The United States has filed a formal protest with China over the decisions.





U.S. officials are baffled about the reason or reasons for the port call refusals. China recently has expressed concerns about U.S. arms sales to Taiwan and President Bush's October presentation of a Congressional Gold Medal to the Dalai Lama, the exiled Tibetan spiritual leader.  Watch China put the blame on the U.S. »





There is speculation that the Chinese may have been conducting military exercises that they didn't want the U.S. Navy to see. Others think the refusals may have been the result of a misunderstanding.





Officials could not explain why the rejection of the Reuben James had not been disclosed before, even though reporters had repeatedly asked if there were any other pending port calls. One senior Navy official expressed dismay that the information had not been made public by the Pentagon.





White House deputy spokesman Scott Stanzel told reporters the White House is "aware" of the latest refusals and referred reporters to the Pentagon. Stanzel said a "clarification" on the matter was being sought from Beijing.





White House and other Bush administration officials have sought to defuse tensions with China, saying the United States wants to move ahead on broader issues of military cooperation.





Navy officials, meanwhile, say Japan is tightening approvals for Chinese navy visits into its ports. Crew members from a Chinese ship making a port call in Japan may not be allowed to tour a Japanese Aegis warship.





The U.S.-designed Aegis weapons system enables coordinated operations against threats from aircraft and missiles, surface ships and submarines.





It is not clear if the Japanese decision was made at the request of the United States. E-mail to a friend
How many U.S. minesweepers were denied safe harbor during a storm? Which country wouldn't let US Air Force jet land? What else did China do? What won't China allow? Which frigate was not allowed to enter Hong Kong?
two China refused nine U.S. Navy ships and one Air Force jet entry to Hong Kong U.S. Navy ships and one Air Force jet entry to Hong Kong USS Reuben James,
question: How many U.S. minesweepers were denied safe harbor during a storm?, answer: two | question: Which country wouldn't let US Air Force jet land?, answer: China | question: What else did China do?, answer: refused nine U.S. Navy ships and one Air Force jet entry to Hong Kong | question: What won't China allow?, answer: U.S. Navy ships and one Air Force jet entry to Hong Kong | question: Which frigate was not allowed to enter Hong Kong?, answer: USS Reuben James,