US President Barack Obama was due to visit Poland on Friday and Saturday to discuss shale gas and US F-16s on Polish soil, in a visit which Warsaw helps will cement its position as one of Washington's strongest allies in central Europe, dpa reported. Obama was to arrive in Warsaw on Friday for a meeting with several heads of state of central and eastern European countries, who will be in Warsaw for a summit at that time. The US leader was set to meet Saturday with Polish President Bronislaw Komorowski and Prime Minister Donald Tusk. The trip will be Obama's first visit to Poland.