WASHINGTON - US President Barack Obama said Tuesday he worries that a Greek default on its debt could have disastrous implications for the US economy.

Speaking in a news conference with German Chancellor Angela Merkel, Obama said that Germany and other European countries needed to act together to help Greece stabilize its economy.

US President Barack Obama presents the Presidential Medal of Freedom to German Chancellor Angela Merkel at an official State Dinner in the Rose Garden at the White House in Washington, June 7, 2011. [Photo/Agencies]

He said that America's economic growth depended on a sensible resolution to Greece's problems.

"We think it would be disastrous for us to see an uncontrolled spiral and default in Europe because that could trigger a whole range of other events," he said.

The news conference came on a day of high pomp at the White House beginning with a 19-gun salute to welcome the German leader. Later, Obama presented Merkel with the Presidential Medal of Freedom during a formal dinner at the White House. The gestures appear aimed at boosting a relationship that has seemed more cordial than close.

The White House even did a little social engineering with Grammy Award-winner James Taylor's playlist for the al fresco gathering.

"They actually specifically suggested 'You've Got a Friend,"' Taylor reported as he arrived. "That's sort of the theme of the evening."

For the first time, the Obamas were serving dinner underneath the skies in the Rose Garden, just steps from the Oval Office. The fare featured tuna tartare and petite filet. The salad came from first lady Michelle Obama's White House garden.

"You look lovely tonight," Obama said to Merkel as she arrived with her husband, Joachim Sauer. Merkel traded in her customary pantsuit for a black gown with short sleeves and an off-center neckline.