This undated photo provided by the U.S. Attorney's Office shows Omar Abdulsattar Ameen. The refugee from Iraq was arrested Wednesday, Aug. 15, 2018, in Northern California on a warrant alleging that he killed an Iraqi policeman while fighting for the Islamic State organization. (U.S. Attorney's Office via AP)

United Nations Secretary-General Antonio Guterres offers flowers during a ceremony at Nagasaki Peace Park in Nagasaki, southern Japan Thursday, Aug. 9, 2018, marking the 73rd anniversary of the bombing on the city. (Takuto Kaneko/Kyodo News via AP)

A woman burns a stick of incense at the cenotaph dedicated to the victims of atomic bombing at Hiroshima Peace Memorial Park in Hiroshima, western Japan, Monday, Aug. 6, 2018, marking the 73rd anniversary of the bombing. (Yohei Nishimura/Kyodo News via AP)

North Korean Lt. Gen. An Ik San, second from right, shakes hands with his South Korean counterpart Maj. Gen. Kim Do-gyun during a meeting inside the Peace House at the border village of Panmunjom, South Korea, Tuesday, July 31, 2018. Generals from the rival Koreas met Tuesday at their shared border for talks meant to ease a decades-long military standoff, Seoul officials said.(Korea Pool/Yonhap via AP)

Representative and former Philippine President Gloria Macapagal Arroyo bangs the gavel after taking the oath as the new house speaker, at the House of Representatives in Quezon city, metropolitan Manila, Philippines Monday July 23, 2018. A leadership row erupted in the Philippine House of Representative, delaying President Rodrigo Duterte's delivery of his annual state of the nation address and passage of a crucial Muslim rebel autonomy deal. (AP Photo/Aaron Favila)

Security removes an apparent protester before a joint press conference between U.S. President Donald Trump and Russia President Vladimir Putin in the Presidential Palace in Helsinki, Finland, Monday, July 16, 2018. (Antti Aimo-Koivisto/Lehtikuva via AP)

A Ethiopian holding an Ethiopian flag waves at the Eritrean president in Addis Ababa, Ethiopia, Sunday July 15, 2018. Official rivals just weeks ago, the leaders of Ethiopia and Eritrea have embraced warmly to the roar of a crowd of thousands at a concert celebrating the end of a long state of war. A visibly moved Eritrean President Isaias Afwerki, clasping his hands over his heart, addressed the crowd in Ethiopia's official language, Amharic, on his first visit to the country in 22 years. (AP Photo/Mulugeta Ayene)

FILE - In this Nov. 11, 2017 file photo, U.S. President Donald Trump and Russia's President Vladimir Putin talk during the family photo session at the APEC Summit in Danang, Vietnam. The outcome of the first summit between the unpredictable first-term American president and Russia’s steely-eyed longtime leader is anybody’s guess. With no set agenda, the summit could veer between spectacle and substance. As Donald Trump and Vladimir Putin head into their meeting, Monday, July 16, 2018 in Helsinki, here’s a look at what each president may be hoping to achieve: (Jorge Silva/Pool Photo via AP, File)

FILE - In this July 7, 2017, file photo, President Donald Trump meets with Russian President Vladimir Putin at the G20 Summit in Hamburg. Trump seems of two minds about nuclear weapons. He has mused about their elimination. But he also has called for a U.S. buildup and bragged about his nuclear "button." How these seemingly competing instincts will play out in his Helsinki talks with Putin on July 16, 2018, could profoundly affect the direction of U.S. defense policy. (AP Photo/Evan Vucci, File)