Urging 71-year-old President Donald Trump to keep former President Barack Obama’s April 2, 2015 Nuke Deal approved in Lausanne, Switzerland, 67-year-old Defense Secretary James “Mad Dog” Mattis sees more costs than benefits backing out of the deal. While there’s little dispute that Iran got the better of the bargain with the P5+1, including the U.S., U.K, France, Russia, China and Germany, the costs of leaving the agreement outweigh the benefits. Mattis, a former four star general, knows how to pick his battles, deciding it’s in the U.S. best interests to keep the two-year-old agreement. Since the 2016 campaign, Trump’s been complaining the U.S. got badly out-negotiated, handing Iran $1.7 billion in cash, releasing some $150 billion in frozen Iranian assets. Mattis sees the big picture that the U.S. can’t spread itself too thin dealing with a crisis on the Korean Peninsula.

Asked by Sen. Angus King (R-Maine) in the Senate Armed Forces Committee whether or not he thought the Iran Nuke deal benefits U.S. national Security, Mattis told King, “Yes, senator, I do.” Trump’s under increasing pressure to certify to Congress Oct. 15 that Iran’s full compliance with the agreement. Testing ballistic missiles falls into a gray area when it comes to compliance. Obama certified to Congress for two years that Iran was in compliance with the April 2, 2015 agreement. Iran’s 57-year-old Foreign Minister Mohammed Javad Zarif, who negotiated the deal with former Secretary of State John Kerry, said that if Trump backs out, Iran would resume its nuclear enrichment activities. Although Iran has denied any military application to its enrichment program, Obama and Kerry thought the deal prevented Iran for 10 years from weaponizing its uranium enrichment program.

Democrats in Congress back the P5+1 Nuke Deal, believing it’s the best way to delay Iran’s military application to its uranium enrichment program. Trump wants to apply more sanctions on Iran’s ballistic missile tests, in effect nullifying the agreement. Mattis’s support to continue the agreement doesn’t give Iran a pass but lets the Pentagon focus on one national security threat at a time. With the situation at a fever’s pitch in the Korean Peninsula, the Pentagon has been preparing 24/7 for the military option in North Korea. Trump has put his credibility on the line saying he won’t tolerate a nuclear-armed North Korea. Most military and ballistic weapons experts believe that North Korea is dangerously close to a nuclear-tippled Intercontinental Ballistic Missile [ICBM], an intolerable threat to U.S. national security. Mattis wants the Pentagon to focus on one major threat at a time.

Mattis doesn’t want the Pentagon to have to prepare for a potentially two-front war, one in North Korea and one in Iran. “If we can confirm that Iran is living by the agreement, if we can determine that this is in our best interest, then clearly we should stay with it,” Mattis said. Trump sees no downside to decertifying the agreement, since Iran has been out-of-compliance since Day One. Iran promised in the agreement to allow unfettered access to all of its nuclear enrichment sites to the U.N.’s nuclear watchdog group, the International Atomic Energy Agency [IAEA]. Iran hasn’t permitted the IAEA to inspect any of its Top Secret military sites, including Parchin, some 30 miles south of Tehran. “I believe, at this point in time, absent indications to the contrary, it is something the president should consider staying with,” said Mattis, knowing war hawks in Congress oppose the agreement.

Mattis wants Trump to keep his focus on North Korea, where the Pentagon has been busy preparing for a military option. While 65-year-old Secretary of State Rex Tillerson said he’s been engaged in some talks with North Korea, it doesn’t mean they’re about disarming North Korean President Kim Jong-un. Russian President Vladimir Putin, in a rare moment of candor Sept.5 , two days after Kim detonated a hydrogen bomb, said Kim would rather “eat grass” than give up his nukes. Trump faces some real challenges preventing North Korea from getting a nuke-tipped ICBM. Mattis wants Trump to keep his focus on North Korea, not Iran. Sen. Tom Cotton (R-Ak.), told Trump Oct. 2 to reject the Iranian agreement. “He didn’t tell me, he said he’s made a decision but he’s no telling anyone. I strongly urged him to not certify the deal,” Cotton told Trump at dinner Monday night.

Trump’s Chairman of the Joint Chiefs of Staff Gen. Joseph Dunford, told Trump last month that Iran was in compliance of the Joint Comprehensive Plan of Action AKA the Iran Nuke Deal. While expressing concern about Iran’s ballistic missile tests, Dunford still believes Iran complies with the spirit of the agreement. When you consider Iran flat-out rejects any renegotiation of the deal, Trump leans toward canceling the deal, despite the fact that Britain, France, Russia, China and Germany could continue the deal. Threatening to ramp up uranium enrichment activity tells the real story behind the flawed agreement. If Iran has no intent to building nuclear weapons as it says, why would the U.S. care if it enriches uranium? Most nuclear experts believe Iran was weaponizing uranium to build nuclear bombs. Given that the IAEA has no access to Iran’s military sites, the weaponizing may have never stopped.