Some powerful players could be missing from a U.S.-hosted nuclear summit later this week in Washington, as Russia says it won’t participate and Pakistan Prime Minister Nawaz Sharif cancels his planned trip.

Indian media outlets reported Monday that Sharif canceled his visit to Washington after the deadly terror attack in Lahore. He reportedly will be represented in Washington by a top adviser.

Russia already said it has no plans to participate in the Obama administration’s nuclear talks set for Thursday and Friday. According to reports, Moscow’s Foreign Ministry says the summits have “played their role,” but now interfere in the activities of the United Nations and other groups. 

The Russian government has until the start of the Nuclear Security Summit on March 31 to reconsider.   

The absence of the Russian government and the prime minister of Pakistan -- both important nuclear powers -- could hinder the talks.

The official website for the summit said “it is unfortunate” Russia decided not to attend, adding, “We hope that Russia, as the host of the first nuclear security summit of ‘G7+1’ leaders in 1996, still shares the view that securing nuclear materials and combatting nuclear terrorism are priorities well worth the personal attention of world leaders.”

Representatives from more than 50 countries still are set to attend the summit. But Russia is considered critical to any discussion on nuclear arms control and security. In 2015, Russia possessed an estimated 7,700 warheads according to, 600 more than the United States.

Eugene Rumer, director of the Russia and Eurasia Program for the Carnegie Endowment for International Peace and a former U.S. intelligence officer for Russia and Eurasia, explained the mindset in Moscow. “Russia will deal with the U.S. as equals where it feels it’s useful. But Russia will not come to Washington to kiss the ring of President Obama,” he told Fox News.

The summit is being held in the shadow of a rash of terror attacks – in Brussels and now Lahore – but also recent nuclear activity. In January, North Korea conducted its fourth nuclear test, and has threatened more. North Korea’s recent provocation is expected to receive considerable attention. China’s president will visit Washington later this week to attend the summit, with North Korea in mind.

Secretary of State John Kerry visited Moscow last week to discuss Syria and Ukraine days after the second anniversary of Russia’s annexation of Crimea. Russian forces remain active in Eastern Ukraine, according to the outgoing U.S. military commander in Europe, Gen. Philip Breedlove.

Kerry met with Russian President Vladimir Putin for four hours and conducted a midnight press conference Thursday night, according to the AP.

Putin thanked President Obama for his help in Syria, without mentioning the nuclear meeting.

“We are aware that the groundwork we have on Syria could only have been possible thanks to the supreme political leadership of the United States, specifically the position of President Obama,” said Putin.   

Lucas Tomlinson is the Pentagon and State Department producer for Fox News Channel. You can follow him on Twitter: @LucasFoxNews