The United States has told the Syrian government to immediately suspend operations at its embassy in Washington and two honorary consulates.
White House spokesman Jay Carney said Tuesday that Syrian diplomats who are not U.S. citizens or permanent residents must leave the country.
"Following the announcement that the Syrian embassy suspended its provision of consular services and in consideration of the atrocities the Assad regime has committed against the Syrian people, we have determined it is unacceptable for individuals appointed by that regime to conduct diplomatic or consular operations here in the United States."
Secretary of State John Kerry highlighted the number of people killed and forced from their homes by three years of fighting, including "people attacked by their own government with gas."
"We just felt that the idea that this embassy is sitting here with representation, that we could take seriously, is an insult. And we closed it. It's that simple. And we'll see what happens in other places, but the Assad regime can never regain legitimacy in Syria. Whether they win, don't win, they can't regain legitimacy."
New U.S. special envoy for Syria Daniel Rubinstein said the U.S. wants to maintain diplomatic relations with the state of Syria as an expression of longstanding ties with the Syrian people, something he said will endure "long after Bashar al-Assad leaves power."
Meanwhile, Israel says its air force bombed Syrian military positions Wednesday in response to an attack on its forces in the Golan Heights. The targets included an army training facility, military headquarters and artillery batteries.
The Israeli military said an explosive device targeting its forces injured four soldiers on Tuesday. A spokesman called the blast "an unacceptable escalation of violence from Syria" and vowed that Israel would not tolerate threats to its forces.
Two weeks ago, Israeli troops shot two fighters from Lebanon's Hezbollah near the fence dividing Israeli and Syrian-held areas of the Golan. The Israeli army said they had been trying to plant a bomb near the barrier.
Israel captured the Golan from Syria in the 1967 war and annexed it in a move not recognized internationally. The strategic plateau has seen occasional spillover violence from the Syrian civil war.
In Geneva, United Nations investigators said Tuesday they have added to their list of suspected war criminals from both sides in the Syrian civil war after a new round of atrocities in recent weeks.
Lead investigator Paulo Pinheiro said the U.N. inquiry has identified military units and security agencies as well as insurgent groups suspected of committing abuses.
He said a newly drafted 'perpetrators list' includes the names of intelligence branches and detention facilities where detainees are tortured, military commanders who target civilians, officials overseeing airports from where 'barrel bomb' attacks originate, and leaders of armed groups who attack civilians.
It is the most specific information revealed thus far about the identities of suspected war criminals on the list.