MOSCOW — Prime Minister Vladimir Putin vowed “retribution is inevitable” for the suicide bombing that killed 35 people at Russia’s busiest airport, while President Dmitry Medvedev demanded robust checks at all transport hubs and lashed out at the airport for lax security.

Putin has built much of his reputation on his harsh stance against terror, but he did not elaborate on what kind of retribution he had planned or for whom in his comments today during a government meeting.

No claims of responsibility have been made for the attack Monday at Domodedovo Airport, which also left 180 people injured.

Suspicion is likely to fall, however, on Islamist separatist insurgents from Chechnya or elsewhere in Russia’s restive Caucasus region who have been battling Russian authority for more than 15 years.