North Korea warned Wednesday of a "thousand-fold" military retaliation against the US and its allies if provoked, the latest threat in a drumbeat of rhetoric in defense of its rogue nuclear program. Japanese and South Korean news reports said North Korea is preparing an additional site for test-firing a long-range missile capable of striking the US. The warning of a military strike, carried by the North's state media, came hours after President Barack Obama declared North Korea a "grave threat" to the world, and pledged that recent UN sanctions on the communist regime will be aggressively enforced. Also on Wednesday, Defense Minister Ehud Barak assessed that a well-orchestrated operation carried out by the US, China and Russia could prevent North Korea from achieving it's goals. "Today, it's much more complicated to divert North Korea from its nuclear program than it would have been several years ago. In the US, in Russia and in China, people are asking themselves 'Why did we wait for Pyongyang to act on their threats?'," he told Army Radio. However, Barak said he believed that even now, "a well coordinated and intelligent operation" by Washington, Moscow and Beijing could "stop North Korean leader Kim Jong-Il from achieving his goals." Obama and South Korean President Lee Myung-bak met in Washington Tuesday for a landmark summit in which the two leaders agreed to build a regional and global "strategic alliance" to persuade North Korea to dismantle all its nuclear weapons. Pyongyang claims its nuclear bombs are a deterrence against the United States and accuses Washington of plotting with Seoul to topple its secretive regime -- led by the unpredictable dictator Kim Jong Il who is reportedly preparing to hand over power to his 26-year-old youngest son. "If the US and its followers infringe upon our republic's sovereignty even a bit, our military and people will launch a one hundred- or one thousand-fold retaliation with merciless military strike," the government-run Minju Joson newspaper said in a commentary. The commentary, carried by the official Korean Central News Agency, also called Obama "a hypocrite" for advocating a nuclear-free world while making "frantic efforts" to develop new nuclear weapons at home. "The nuclear program is not the monopoly of the US," it said without mentioning the Obama-Lee summit. Attention has been focused on North Korea since it conducted a nuclear test, its second, on May 25 in defiance of the United Nations. The UN Security Council responded by toughening an arms embargo, authorizing ship searches for nuclear and ballistic missile cargo and depriving the regime of the financing used to build its nuclear program. South Korea's Dong-a Ilbo newspaper reported Wednesday that the North has begun withdrawing money from its bank accounts in the Chinese territory of Macau and elsewhere, for fear they would be frozen under the UN sanctions. Separately, Japan's Sankei newspaper said Wednesday that the North has been showing signs of preparing two sites, one on the northeastern coast and one on the northwestern coast, from where a long-range missile could be launched. It was earlier thought that any launch would come only from the northwest. South Korea's Chosun Ilbo newspaper also carried a similar report Wednesday, quoting an unidentified government official as saying that a special train that carried a long-range missile to the northwestern site has recently moved to the northeastern site. South Korea's Unification Ministry, Finance Ministry and the National Intelligence Service said they could not confirm the reports on money withdrawals or on the long-range missiles, which ostensibly can carry a nuclear warhead. North Korea, which conducted its first nuclear test in 2006, is believed to have enough weaponized plutonium for at least half a dozen atomic bombs. It revealed last week that it is also producing enriched uranium. The two materials are key ingredients for making atomic bombs. The recent moves by North Korea have effectively brought to a halt the so-called six-party talks aimed at giving North Korea fuel and other benefits in exchange for dismantling its nuclear program. The talks involved the two Koreas, the US, Japan, China and Russia. Obama said the US is more than willing to negotiate with North Korea to bring peace on the Korean peninsula. "But belligerent, provocative behavior that threatens neighbors will be met with significant and serious enforcement of sanctions that are in place," he said. Pentagon officials also warned Tuesday that North Korea's missiles could strike the US within three years if its weapons growth goes unchecked. Some analysts believe that the North's rhetoric is aimed at showing people at home that their government can defy the powerful US, and giving credit for it to Kim's reported heir apparent, Kim Jong Un. The analysts say this would make Jong Un's ascent to the top acceptable to the North Koreans.