WASHINGTON — President Obama on Saturday refused to give a time limit on America’s renewed military involvement in Iraq, saying he doesn’t think “we are going to solve this problem in weeks” as the country struggles to form a new government.

“I think this is going to take some time,” he said at the White House before departing for a vacation on Martha’s Vineyard off the Massachusetts coast.

Obama warned Americans that the new campaign to bring security in Iraq requires military and political changes and “is going to be a long-term project.”

The president said Iraqi security forces need to revamp to effectively mount an offensive, which requires a government in Baghdad that the Iraqi military and people have confidence in. Obama said Iraq needs a prime minister – an indication that suggests he’s written off the legitimacy of the incumbent, Nouri al-Maliki.

Obama said he will not close the U.S. Embassy in Baghdad or the consulate in Irbil, which means American troops and diplomats will remain on the ground. He said he is obligated as commander in chief to protect U.S. personnel wherever and whenever they are threatened.

The president said humanitarian efforts continue to airdrop food and water to persecuted religious minorities stranded on a mountaintop, and he said planning was underway for how to get them down.

Obama said he spoke to French President Francois Hollande and British Prime Minister David Cameron on Saturday morning about joint humanitarian efforts and that both expressed strong support for his actions. Cameron’s office said the British Royal Air Force will start dropping supplies for the estimated 50,000 to 150,000 people trapped on Mount Sinjar.

The president repeated that the U.S. will not have U.S. combat troops in Iraq again. “We are going to maintain that because we should have learned a lesson from our long and immensely costly incursion into Iraq,” Obama said.

He dismissed the suggestion that the new military action in Iraq might cause him to regret pulling out troops in the first place.