President Reagan, welcoming Andrei D. Sakharov at the White House, said today human rights will remain an irritant in U.S.-Soviet relations until all political prisoners are released. ``We've had great success,'' Reagan said as he praised Soviet President Mikhail S. Gorbachev as more cooperative than any Kremlin leader before him. But, Reagan said, ``We can only wait and see'' if Gorbachev makes good on a promise to release all political prisoners. Sakharov told the president as they posed for pictures that ``there are only individuals'' left in jails. The Nobel laureate and human rights activist spoke through an American interpreter. White House spokesman Marlin Fitzwater said that during their meeting, Sakharov ``was very thankful'' to Reagan ``for what he had done on behalf of human rights and for him and his wife.'' Sakharov, however, also voiced concern about the impact that Reagan's ``Star Wars'' missile defense program would have on efforts by the superpowers to negotiate a cut in long-range nuclear missile stockpiles. These statements led Reagan to talk about the ``insurance policy'' concept behind development of the Strategic Defense Initiative, according to Fitzwater, who also said that the president told Sakharov that while there is a treaty to ban chemical weapons, ``we still keep our gas masks.'' Sakharov says the West should worry more about the possibility that Gorbachev will fail in his bid to transform Soviet society, and less about whether the changes will strengthen the communist nation. Sakharov, the Soviet Nobel Peace Prize-winning physicist and longtime spokesman for political prisoners and dissidents, told those honoring him Sunday at a National Academy of Sciences banquet that the effects of perestroika _ the ambitious economic restructuring pursued by Gorbachev _ will ripple throughout the world. He said some have suggested that the Soviet Union could pose an even greater threat to the West if the Soviet economy is strengthened. ``I always answer that question this way,'' he said through an interpreter. ``The threat (to the West) of perestroika doesn't consist of its success, but of its bloody failure. This would be a total calamity.'' The program pushed by Gorbachev, the Soviet general secretary, includes greater freedoms and movement away from a centrally controlled economy. ``I believe we are undergoing historic events whose significance extends beyond our country to the whole world,'' said Sakharov. Sakharov, 67, was sent to internal exile in the Soviet city of Gorky in 1980 after criticizing the Soviet invasion of Afghanistan and the immigration policies of his country. Gorbachev freed him two years ago. Sakharov first made his mark as a physicist whose original concepts in subatomic particles attracted world attention among scientists. He is considered the father of the Soviet hydrogen bomb. Frank Press, president of the National Academy of Sciences, told the banquet guests that Sakharov was inducted into the American academy in 1973 as an associate member. But unlike other members, Sakharov had never been allowed to come to the United States to sign the membership book. While guests applauded, the Soviet scientist strolled to the large, red-bound ledger and signed his name. Sakharov said that during his long years of exile, the American academy members ``supported me unequivocally.'' ``This is a fact I can never let myself forget,'' he said. The 100 guests who attended the banquet included other Soviet scientists, noted American physicists, physicians, arms control negotiators, human rights advocates and government officials. Sakharov is in Washington to attend the first meeting of the International Foundation for the Survival and Development of Humanity. The foundation was organized by U.S. and Soviet scientists to address social and scientific problems that affect mankind.