From the New York Times, Jan. 13, emphasis added:

ATHENS, Jan. 12 — An antitank grenade was fired into the heavily fortified American Embassy here on Friday just before dawn. The building was empty, but the attack nonetheless underscored deep anti-American sentiment here and revived fears of a new round of homegrown terror.

Greek officials said they doubted that the attack was the work of foreign or Islamic terrorists, but rather that of regrouped extreme leftists aiming at a specific, symbolic target: the huge American seal, with an eagle against a blue background, affixed to the front of the boxy, modern embassy near downtown.

The grenade narrowly missed the seal, punching through a window a few feet above and landing in a bathroom on the embassy’s third story, where the ambassador has his office.

The damage was described as minimal. But the ambassador, Charles Ries, said: “We treat it as a very serious attack. There can be no justification for such a senseless act of violence.”

Panayiotis Stathis, a spokesman for the Public Order Ministry, said, “This was a violent act aimed to provoke Greek public opinion and disturb relations with the United States.”

As Mr. Stathis spoke to reporters Friday evening outside the embassy, a demonstrator waved a sign that underscored Greece’s often uneasy relations with the United States on issues from the war in Iraq and the longstanding tensions between Greece and Turkey to the American-supported military dictatorship that ruled Greece from 1967 to 1974. “The C.I.A. was behind this,” the sign read.

Greek officials said a phone call placed anonymously to a private security company used by the embassy stated that the attack had been carried out by Revolutionary Struggle, a Marxist group with strong anti-American sentiments.

Homegrown terror has largely waned since the Greek authorities dismantled the most deadly groups before the 2004 Olympic Games here. But in that relative lull, Revolutionary Struggle has emerged as the most active of a new generation of small, shadowy terrorist groups.

It has claimed responsibility for a bombing at a court building in Athens in 2003 and one at the Economics Ministry 13 months ago, an attack that wounded two people. It also claimed responsibility for an attempt last May to assassinate the culture minister.

Greek officials did not immediately accept the claim of responsibility for Friday’s incident, as they waited for a more detailed proclamation from the attackers.

“We’re investigating whether in fact this claim is true,” Vyron Polydoras, the public order minister, told reporters after visiting the embassy, which was closed for the day, its flag hung at half-staff.

Maria Bossis, one of Greece’s top terrorism experts, speculated that the attack had a purpose beyond making a strong and violent anti-American statement. She said she believed that the group was also aiming at establishing supremacy among the 10 groups in competition since the government dismantled November 17, the most notorious of the leftist terrorist groups.

“This attack will determine who the boss is among the terrorists,” said Ms. Bossis, a professor at the Greek College of Defense and former government adviser.

She also said the Greek government had not remained as aggressive against terrorists as it had been before the Olympics.

The grenade was launched at 5:58 a.m., apparently from across the six lanes of Vassilisis Sophia Boulevard, the main north-south road in the central Athens neighborhood of Ilissia.

See our last posts on Greece and its armed left underground.