President Barack Obama says U.S. aircraft are positioned to strike any ISIS forces that threaten Erbil in Northern Iraq.

In a statement from Martha's Vineyard, Obama said some of the Iraqis who were trapped by ISIS fighters on Mount Sinjar have been able to escape their situation.

President Obama also gave his approval to the appointment of a prime minister to replace Nouri al-Maliki and urging the formation of a new government in Iraq as soon as possible. The president called the move a "promising step forward." 

Obama said he and Vice President Joe Biden had spoken with Haider al-Ibadi, who was designated prime minister by the new president.

Obama also said the United States had successfully carried out targeted air strikes to support Kurdish fighters in their battle against Islamist extremists, and conducted humanitarian relief missions to aid thousands of stranded women and children on a mountain in Iraq.

He said the only lasting solution in Iraq is the formation of an inclusive government.

The Associated Press contributed to this report.