Seoul, South Korea (CNN) North Korea is believed to be moving an intercontinental ballistic missile (ICBM), a South Korean lawmaker said after being briefed by the country's intelligence service. 
 
 The lawmaker told CNN Tuesday it was unclear when the movement was detected, what the direction of the projectile was and how it was being transported. He attended the briefing by South Korea's National Intelligence Service (NIS) in Seoul on Monday. 
 
 All eyes have been on North Korea following the country's sixth test of a nuclear weapon Sunday. Seismological data indicated the weapon was the most powerful ever detonated by the rogue nation, nuclear experts said. 
 
 North Korean state media claimed it detonated a hydrogen bomb, also known as a thermonuclear weapon, which could be fitted atop a long-range missile capable of striking the United States. 
 
 Weapons experts say it's almost impossible to verify if the warhead and missile could be successfully paired unless North Korea were to actually fire a nuclear-tipped ICBM. 
 
 The country has test-fired a number of missiles this summer, including two long-range ones in July and an intermediate-range one in August that overflew the Japanese island of Hokkaido. 
 
 Lawmaker Kim Byung-kee told reporters Monday after the same briefing that the NIS said North Korea may test-fire an ICBM towards the North Pacific at a lower angle than the two tests in July, which were lofted, meaning they flew higher but not as far. 
 
 Live-fire drills 
 
 The South Korean Navy announced Tuesday it conducted live-fire drills off the east coast of the Korean Peninsula to check its "immediate operational readiness" after the country's Air Force and Army conducted their own joint drills. 
 
 South Korea's Navy conducted a live-fire drill in the waters off the east coast of the Korean Peninsula in response to North Korea's Sunday nuclear test. 
 
 "Wherever it is, whether on or under water, if North Korea provokes, we will immediately destroy and bury them at sea," the Navy said in a statement. 
 
 While South Korean forces have flexed their muscles, diplomats in New York gathered at the United Nations and condemned the nuclear test. 
 
 Nikki Haley, the American ambassador to the United Nations, said Monday the United States would circulate a resolution in response after urging her colleagues to adopt the strongest sanctions measures possible to stop Pyongyang's nuclear program. 
 
 "Enough is enough," Haley said. "North Korea has basically slapped everyone in the face in the international community that has asked them to stop." 
 
 Another lawmaker who attended the Monday briefing, Lee Cheol-woo, told reporters the NIS informed them that Pyongyang had dug extra tunnels at the nuclear test site and could explode another one "anytime." 
 
 Rift? 
 
 South Korean President Moon Jae-in and his American counterpart, President Donald Trump, spoke by phone Monday and agreed to lift current restrictions on the payload weight of South Korea's ballistic missiles, according to a South Korean presidential spokesman. 
 
 But signs of a rift between the two leaders have become apparent despite the decades-long alliance between Seoul and Washington. 
 
 Their phone call came a day after the nuclear test and followed a tweet from Trump in which he criticized South Korea for "appeasement" when it comes to dealing with its northern neighbor. 
 
 Moon has long been a proponent of more dialogue and diplomacy with North Korea, whereas Trump has said recently that "talking is not the answer." 
 
 "This is not the time for these two countries to be showing these cracks. North Korea is going to exploit that," said Jean Lee, a North Korea expert and global fellow at the Wilson Center. 
 
 Trump spoke twice with Japanese Prime Minister Shinzo Abe over the weekend, once before the nuclear test and once after. 
 
 Diplomacy 
 
 Moon and Abe are both traveling to the eastern Russian city of Vladivostok for an economic summit taking place Wednesday and Thursday. 
 
 They will be joined by Russian President Vladimir Putin, who is currently in China for a summit of the BRICS nations -- Brazil, Russia, India, China and South Africa. He reiterated calls for North Korea to stop nuclear tests but said dialogue needs to be the answer. 
 
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 "Russia condemns these exercises from North Korea. We think these exercises are provoking in nature but we should not forget and North Koreans should not forget what happened in Iraq," he said. 
 
 "Sanctions of any kind are usefulness and ineffective ... they will eat grass but they will not turn away from the path that will provide for their security," Putin said, referring to accusations that Pyongyang spends too much on weapons programs while its citizens starve. ||||| An ICBM test by North Korea on Sept. 9? 9:04 PM ET Sun, 3 Sept 2017 | 02:51 
 
 North Korea could launch yet another missile as soon as Saturday when the country celebrates its founding day, hot on the heels of its biggest-to-date nuclear test. 
 
 "I think another ICBM [intercontinental ballistic missile] test ... could come on Sept. 9. The North Koreans love to put on a big show for their big national holiday," said Harry Kazianis, director of defense studies at the U.S.-based Center for the National Interest. 
 
 In fact, one of the pariah state's previous nuclear trials fell on Sept. 9, 2016. 
 
 For North Korea, the timing of weapons tests is of strategic importance. 
 
 "They're going to want to get the most attention they can," Kazianis told CNBC in August. That means Pyongyang is unlikely to provoke at a time when it expects another major event to be dominating the headlines, he suggested.
– Following North Korea's most powerful weapons test yet on Sunday, a South Korean lawmaker tells CNN his country's intelligence service believes the North has an intercontinental ballistic missile (ICBM) on the move. Things get pretty vague beyond that: He didn't know the method of transport or when the movement was noticed. But Reuters does pick up some alleged details on those fronts, via an unnamed source quoted by South Korea’s Asia Business Daily. Its source says the ICBM started moving Monday, is only being moved at night, and is headed toward the nation's west coast. Reuters notes there's some likelihood that another test could come on or around Saturday: Sept. 9 is the country's founding day holiday. CNBC notes North Korea conducted a nuke test on Sept. 9, 2016. Two more details that allegedly came from the South's National Intelligence Service briefing: word that additional tunnels have been dug out at the North's nuclear test site that would facilitate future detonations, and suspicions that the next ICBM test firing might be directed toward the North Pacific but aimed at a lower angle, which would in theory allow it to fly further than previous tests, which had more of an upward trajectory. Meanwhile, the White House tells Reuters it has given "in-principle approval" to a request by South Korean President Moon Jae-in to abolish a limit regarding warhead weights, a move that would strengthen the power with which it could attack the North, if necessary. Meanwhile, Vladimir Putin on Tuesday gave his take on the situation: North Korea "will eat grass but will not give up the (nuclear) program if they don't feel safe."