Riyadh has been part of the coalition carrying out airstrikes against extremists since last year

US President Barack Obama led a heavyweight delegation in Saudi Arabia on Tuesday to meet with new King Salman, and discussed the two countries' ongoing fight against the Islamic State group, as well as the issue of Iran's nuclear program, a senior US official said.

Riyadh has been part of the US-led coalition carrying out airstrikes against the group since September and is a longtime regional ally of Washington.