A day after at least one suicide bomber murdered 35 people and injured more than 100 more in a Moscow airport, Russian President Dmitry Medvedev said the attack "shows that there were clearly breaches in security" at the airport -- including vulnerabilities American transportation officials are scrambling to address halfway around the world.
Medvedev said in a statement today that tougher security legislation had been created following previous terrorist attacks on Russian transportation hubs, "but unfortunately -- and that is our biggest problem -- we do not always enforce even the most important legislation.
"The airport is good, everyone recognises that, it is new and modern. But what has happened shows that there were clearly breaches in security, and everyone who makes decisions here, including the airport management, will answer for this," he said. "This is an act of terror. This is grief. This is a tragedy."
In a meeting with Russia's security service, the FSB, Medvedev said security at the airport had slipped into a state of "simply anarchy."
The attack, which has not been claimed by any group, took place in the arrivals hall of Domodedovo airport -- a space that, like in American airports, is open to the public and not subject to security screening.
CLICK HERE to see raw video of the explosion, as captured by security cameras.
Just hours after reports of the attack emerged, the U.S. Transportation Security Administration said that passengers traveling through U.S. airports "may continue to notice unpredictable security measures," including some before they reached official security checkpoints.
"We are monitoring the tragedy at Moscow's Domodedovo airport. As always, we are working with our international partners to share information regarding the latest terrorist tactics and security best practices," the TSA said in a statement Monday. "Passengers may continue to notice unpredictable security measures in all areas of U.S. airports, including before the checkpoint. These measures include explosive detection technology, canine teams and Visible Intermodal Prevention and Response (VIPR) teams, among other measures both seen and unseen."
One of the most controversial of those "unseen" measures is a program called SPOT, instituted in 2006, which relies on thousands of "Behavior Detection" officers who are trained to identify deception in potential flyers. The Government Accountability Office has criticized the $212-million federal program, asserting it is based on unproven behavioral science and said at least 17 known terrorists have slipped through as many as 23 U.S. airports running the SPOT program without detection.
CLICK HERE to read ABC News' full report on the SPOT program.
"Every airport in the world, including every airport in the United States, has virtually no security until you get to the security checkpoint," said Richard Clarke, an ABC News consultant and former White House counter-terrorism official. "Very large parts of all airports are inherently insecure."
Expert: Attack Unclaimed, But Fits a Pattern
The blast erupted in the arrivals area of the Domodedovo airport at 4:40 p.m. Moscow time Monday. In addition to the 35 dead, another 130 were injured in what investigators called a suicide bombing at the country's busiest airport.
Evgeny Khorishko of the Russian Embassy in Washington, D.C., told ABC News Monday it was "too early to say" who may have been responsible.
Initial reports published early Monday by Russia's state news agency RIA said witnesses had seen two suicide bombers carry out the attack. Later reports pointed to a single attacker. On Twitter, one purported eyewitness, Ilya Likhtenfeld, said the bomb was on a man standing in a crowd near a cafe.
U.S. President Barack Obama said he "strongly condemns this outrageous act of terrorism against the Russian people" and offered his condolences to those affected, according to a statement read today by White House press secretary Robert Gibbs. The U.S. State Department said it has no indication that any Americans were among those killed or injured.
Video taken inside the airport apparently minutes after the bombing shows the blast area full of smoke, with luggage scattered around the ground. Several bodies, prone and unmoving on the ground, are also visible.
No hard evidence has emerged yet to link the Domodedovo bombing to any specific terrorist group. However, according to counter-terrorism expert Richard Clarke, it fits the pattern of a persistent Chechen campaign of violence.
"This is part of a pattern where the Chechen rebel group attacks in Moscow or in Russia – a major attack about every two years," Clarke said Monday. "They've attacked in the metro, they've attacked in schools, they've attacked in apartment buildings… This is a regular pattern."
Suicide bombers, often female, from Chechnya or Dagestan and sometimes known as "black widows," have carried out many attacks on Russian targets in the past decade, including the simultaneous bombings of two planes mid-flight that killed 90 people in the summer of 2004 and a Moscow metro bombing that killed 10 a week later.
Chechen Militant Leader Had Warned of Attacks to Come
"Black widows" are often avenging the deaths of relatives at the hand of federal forces.
Last March, two female suicide bombers attacked the Moscow subway, killing 40 people and injuring more than 100.
Both women were from Dagestan in the restive North Caucasus region where Russian forces have been battling an Islamist insurgency. One was a 28-year-old schoolteacher, the other the 17-year-old widow of a local militant leader who was killed by Russian forces in 2009.
A Chechen militant leader, Doku Umarov, claimed he ordered the metro attack and warned of more attacks to come in a video posted online.
"Both of these operations were carried out on my command and will not be the last," Umarov said.
On Jan. 21, three days before the Domodedovo bombing, Russia's prime minister, Vladimir Putin said Russia must combat terrorism in the North Caucases by improving the quality of life for the people there.
"Our objective is to radically change the situation in the North Caucasus, primarily by improving the quality of life of the people, ensuring their security and giving them the opportunity to work and live in peace," Putin said. "We must eradicate the roots of terrorism and extremism, first of all poverty, unemployment, ignorance and inadequate levels of education, and corruption and lawlessness."
ABC News' Max Karmen contributed to this report.