intelligence community's assessment is that Iran is in compliance right now with the international nuclear deal.

The nation's top military officer said Tuesday that despite elevated tensions and threats from Pyongyang, the U.S. has not detected any unusual military activity by North Korea. "While the political space is clearly very charged right now, we haven't seen a change in the posture of North Korean forces," said Marine Corps Gen. Joseph Dunford, the chairman of the Joint Chiefs of Staff. "We watch that very carefully." Dunford, speaking at his reappointment hearing before the Senate Armed Services Committee, also said the U.S. military has "postured our forces to respond in the event of a provocation or a conflict. We also have taken all the proper measures to protect our allies — the South Koreans, the Japanese, the force as well as Americans in the area." The general also agreed with the contention that the primary motivation for North Korea having nuclear weapons is for regime survival. He said a pre-emptive military strike on North Korea, which some have suggested as an option, poses serious risks.

Joint Chiefs of Staff Gen. Joseph Dunford Tom Williams | CQ Roll Call | Getty Images

"When we do something, we shouldn't assume at that point that we can control escalation. So we need to think about this in terms of what might happen, as well as what we would want to happen." Dunford also said the greater Seoul area, with about 25 million people, is especially vulnerable because of its proximity to North Korea. He also said there are about 250,000 Americans on any given day in the Seoul area who also "would be threatened by the rockets and the missiles along the border." In May, President Donald Trump nominated Dunford to a second two-year term as chairman of the Joint Chiefs of Staff, the nation's highest-ranking military officer and the principal military advisor to the president, secretary of Defense and National Security Council. President Barack Obama originally appointed Dunford in 2015. Meantime, there's been heated rhetoric recently between North Korea's leader, Kim Jong Un, and Trump, who last week in an address at the United Nations mocked Kim as "Rocket Man" and said the U.S. could "totally destroy North Korea." Kim responded to Trump by calling him a "mentally deranged U.S. dotard." The hermit regime followed it up by releasing a propaganda video this week showing its missiles attacking a U.S. aircraft carrier and U.S. military planes. Also, North Korea foreign minister, Ri Yong Ho, on Monday accused Trump of declaring war against the nation and threatened that the North has the right to shoot down U.S. strategic bombers even if they are flying in international airspace. The North's foreign minister previously told reporters the country might detonate a hydrogen weapon in the Pacific. Sen. James Inhofe (R-Okla.) asked Dunford about his confidence in the assessment by the Defense Intelligence Agency that North Korea will be able to "reliably" reach the U.S. mainland with a nuclear-tipped intercontinental ballistic missile by the end of 2018. The senator added that the agency had once forecast it wouldn't be until 2020 that the North would have the capability.

"Whether it's 3 months or 6 months or 18 months, it is soon," Dunford responded. "We ought to conduct ourselves as though it's just a matter of time and a matter of very short time before North Korea has that capability." Dunford also agreed with Inhofe that it's especially difficult to get intelligence on North Korea even with the U.S. military's aerial snooping capabilities. "The North Koreans over time have buried much of their capability underground, which creates new challenges," said the general. "There's also some specific weather challenges in North Korea that limits our collection at various periods of time." Besides satellites, the U.S. uses reconnaissance aircraft to monitor the North Koreans along with other means. However, Dunford indicated that the U.S. military has faced other challenges over time in constantly tracking North Korea because of needs it sometimes has in other hotspots around the globe. "Part of it also has been the competing demand for a limited amount of intelligence, surveillance and reconnaissance," said the general. "Certainly over the last 18 months, we have increased our collection against North Korea. But for a long period of time we had decreased our collection against North Korea." Dunford also was asked about North Korea perhaps sharing its missile and other military technology with Iran. "We have looked at the nexus quite a bit," said Dunford. "I'm not sure we've seen any transfer of nuclear technology, but we certainly have seen missile technology and a wide range of other weapon systems that they have exported or expertise that they have exported outside of North Korea." The Obama-era Iran nuclear deal and Iran's increased military presence in other countries also came up during the hearing. There's a congressional requirement that the administration provide an assessment to Congress of Iran's compliance with the so-called Joint Comprehensive Plan of Action (JCPOA) every 90 days. Sen. Mazie Hirono (D-Hawaii) asked the general whether it was in America's national security interest to keep the JCPOA. Dunford said it was the intelligence community's assessment that Iran is "in compliance right now. Therefore, we should focus on addressing the other challenges — the missile threat they pose, the maritime threat they pose, the support of proxies, terrorists, and the cyber threat they pose." Even so, the general said he doesn't plan to publicly share the advice he will give to the president on the Iran nuclear deal until Trump has announced a decision. The Trump administration has certified Iran's compliance twice under the law, and the next deadline to provide an assessment is Oct. 15. Trump, who had been sharply critical of the Iran nuclear deal, has indicated he's made his decision on whether Iran is in compliance but hasn't shared it. In his written testimony to the Senate panel, Dunford said Iran hasn't changed its "malign" activities since the 2015 Iran nuclear deal went into effect. However, Sen. Tom Cotton (R-Arkansas) asked the general if Iran had "increased the pace or scope of their malign activities." "I think you can argue that they (Iran) have certainly in Syria," Dunford responded. "It's been relatively consistent in Yemen with regard to their support for the Houthis, and clearly their support for Lebanese Hezbollah has been at a high level for some period of time. And you can argue over the last few months, whether it's related to JCPOA or not, that Iranian activity inside Iraq has certainly increased as they look to the end game in Iraq." Finally, Dunford said if U.S. forces are threatened by Iran "they are both postured and capable of effectively responding."

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