By Julian Ryall in Tokyo The underground nuclear test conducted by North Korea on Wednesday may have been billed as an early birthday present for Kim Jong-un, the North Korean leader, but analysts believe the regime has timed its latest show of force carefully. "North Korea has announced that it will hold its first party congress in 35 years in May and Mr Kim may not feel that he has done enough to cement his position, so showing that he now has a hydrogen bomb is calculated to significantly boost his standing," Toshimitsu Shigemura, a professor at Tokyo's Waseda University and an authority on the North Korean leadership, told The Telegraph. "I also believe that by carrying out the test now, Mr Kim has three months to soothe relations with China, which is still his most important ally," he added. Beijing is additionally concerned about unrest at home over the uncertain economic situation and will shy away from any course of action that might provoke further domestic disquiet. Another consideration will have been Western governments' preoccupation with events in the Middle East, particularly given the escalating crisis between Saudi Arabia and Iran. Given other global flashpoints, analysts believe the international community may be unable to muster much of a response and that Mr Kim may have calculated wisely. "This has come as a serious shock in South Korea and my sense is that there are no feasible options to stop Pyongyang on this path," said Rah Jong-yil, a former head of South Korean intelligence. "The international community will condemn these actions, but we have no effective way of counteracting this development," he said. "Even China, which has acted as a stabilising force in the past, does not have so many cards to play." Prof Shigemura expects Pyongyang to be more conciliatory again later in the year, after the dust from the test has settled and Mr Kim has been able to demonstrate his mastery of his enemies at the Party Congress. "He has demonstrated to his military that they are a powerful nuclear state and I believe we will see a change in his tactics, such as efforts by the North to rebuild ties with China and the United States," he said. That would echo the tried-and-tested approach by the regime over several decades that has promised detente and cooperation but served only to buy time for Pyongyang to develop nuclear weapons and the long-range missiles with which to deliver to them. "Mr Kim wants to negotiate from a position of strength and he has been closely watching the resolution of Iran's nuclear situation", Prof Shigemura added. "And President [Barack] Obama is entering his final year in office and many previous US leaders have tried to make progress on the Korea question as their terms come to an end; Mr Kim may very well be expecting the president to do something similar and offer talks."