US President Barack Obama opened his vacation Friday with a briefing from his top anti-terror aide, after the White House countered Republican mockery of his holiday plans.

John Brennan, assistant to the president for homeland security and counter-terrorism, conducted Obama’s daily intelligence briefing on the president’s first morning at secluded Blue Heron Farm on Martha’s Vineyard.

The White House issued a photograph of Obama, stern faced and wearing a golf shirt during the briefing, apparently trying to counter Republican claims that the president was shirking his duties by going on vacation.

Officials do not divulge the contents of the presidential briefing, but it went ahead at a time of escalating fighting between Moamer Kadhafi’s forces in Libya and a US call Thursday for Syria’s President Bashar al-Assad to go.

The White House also said Obama received a paper briefing from his economic team.

Aides said Obama would mix his official duties with rounds of golf, and activities with his family, but by lunch time he had not ventured off the property, which is surrounded by woodland and fields where cows graze.

Obama aides said that Americans would not begrudge the president a few days of rest with his family.

“The president of the United States is the president of the United States, wherever he goes. That’s the job he ran for. That is what the American people expect. And it’s the job he’s doing,” said Obama spokesman Joshua Earnest.

A top economic official, Brian Deese, will arrive on the island off Massachusetts next week to keep Obama up to speed on fast moving financial issues, as global stocks tank and fears mount of a double dip recession.

Republicans, seeking to further wound a weakened president, have loudly criticized Obama’s decision to spend 10 days on an island known as a summer retreat for millionaires.

Former vice presidential nominee Sarah Palin told Fox News that Obama’s vacation was “very, very tone deaf” at a time of deep economic gloom.

“I think he is going to hear from enough Americans that he will come back early. I think he is going to keep his head in the sand there in Martha’s Vineyard.”

Republican presidential front runner Mitt Romney also took a shot.

“If I were president today, I wouldn’t be looking to go spend 10 days on Martha’s Vineyard,” he told WLS 980 Radio in Chicago on Wednesday.

“If you’re the president of the United States, and the nation is in crisis, and we’re in a jobs crisis right now, then you shouldn’t be out vacationing.”

The Republican National Committee meanwhile created a website at Obamagetaway.com featuring mocked-up postcards of Obama in various pursuits, including biking, playing basketball, surfing and carrying a beach towel.

One card featured a famous picture of a bare chested Obama walking out of the Hawaii surf with the slogan “It’s hot outside, heading to take a double dip,” playing on renewed fears of a slump back into recession.