Former US President Jimmy Carter on Tuesday called on Germany to take the lead in solving the European migrant crisis, a situation he compared to the flow of Vietnamese and Cambodian refugees to the United States during his presidency.Carter, speaking at his annual "Conversation with the Carters" event at the Carter Center in Atlanta, recalled that the United States accepted some 12,000 Southeast Asian refugees a month in the late 1970s following the Vietnam War, hoping to set an example for other countries."I'm hoping there will be a similar reaction maybe with Germany leading," Carter, who served as president from 1977 to 1981, said of the response to the thousands of refugees who have fled war-torn Syria and are arriving in Europe.The former president said the ultimate solution to the migrant crisis was to revolve the war in Syria, and urged the United States to work more closely with Russia and Iran to end the war.Carter also called for more aggressive US action against Islamic State."I would not, at least publicly, favor sending ground troops in (to Syria)," he said. "But I think we could have better surveillance on our bombing and better analysis of what is going on there."The 90-year-old former chief executive, who last month announced that cancer had spread from his liver to his brain and that he would begin radiation treatment, spoke for an hour, mostly on his non-profit centers' global humanitarian efforts.He briefly mentioned the treatment and did not accept questions from the audience about his health.In addition to radiation, Carter said he has received a second treatment of a drug called pembrolizumab, joking that "it took me three weeks to learn how to say that."So far there have been no ill effects from the drug, he said, adding: "As far as what the positive effects were, we won't know until later on."The treatment requires heavy fluid intake and Carter said, "Instead of getting productive work done, I spend a lot of time in the restroom."