SEOUL, Nov 17 (Reuters) - North Korea fired a ballistic missile on Thursday as it warned of "fiercer military responses" to U.S. efforts to boost its security presence in the region with its allies, saying Washington is taking a "gamble it will regret".North Korea has conducted a record number of such tests this year, and also fired hundreds of artillery shells into the sea more recently as South Korea and the United States staged exercises, some of which involved Japan."The keener the U.S. is on the 'bolstered offer of extended deterrence' to its allies and the more they intensify provocative and bluffing military activities ... the fiercer the DPRK's military counteraction will be," Choe said in a statement carried by the official KCNA news agency."We urge an immediate halt of North Korea's series of ballistic missile launches, which is a grave provocation damaging peace and stability," the joint chiefs said in a statement."North Korea has also achieved some political effects by codifying its nuclear law in August, so it might not have immediate needs for a nuclear test," Kwon said in an interview with Yonhap news agency released on Thursday."