The United States and Hungary signed a civilian nuclear cooperation agreement on Monday, as the Trump administration deepened bilateral ties with a controversial ally at a politically sensitive moment for Budapest. U.S. Secretary of State Marco Rubio was in Budapest for meetings with Hungarian Prime Minister Viktor Orbán and senior members of his government, during which Rubio and  Orbán signed the pact. The deal comes two months before Hungary's next parliamentary elections, which may determine whether Orbán can maintain his two-decade grip on power. What is in the U.S.-Hungary nuclear dealThe U.S. and Hungary signed a Memorandum of Understanding on Nuclear Energy in…