North Korea accused President Barack Obama's government of meddling in its internal affairs Wednesday and vowed to take "every necessary measure" to defend itself against what it calls US threats. The statement by North Korea's Foreign Ministry, however, was far less harsh than rhetoric issued by the country's military during the run-up to joint US-South Korean war games that started across the South on Monday. The North's military has threatened South Korean passenger planes and put its troops on standby. Still, the Foreign Ministry's statement was significant in that it was the agency's first on the US since Obama's inauguration, an analyst said. "The Foreign Ministry is Washington's direct negotiating partner and has not engaged in criticizing the US so far," said Kim Yong-hyun, a professor at Seoul's Dongguk University. "This means they have started expressing pent-up complaints." However, the ministry's less strident tone than other agencies reflects Pyongyang's willingness for negotiation, Kim said.