Monday marks one month since the deadly terrorist attack at a concert

hall near Moscow. The Russian government has reportedly been stepping up security measures, and that apparently includes a crackdown on illegal immigration.

More than 140 people have died, due to the incident on March 22. It was the deadliest terrorist attack in Russia in two decades.

The Islamic State group is believed to be responsible for the assault. Four Tajik nationals have been charged with carrying out the attack.

A survey conducted in Russia indicates that an increasing number of people there feel threatened by terrorism.

Many people told NHK crew members in central Moscow that the authorities should toughen measures on immigrants from central Asia. One woman said that she wants the police to keep monitoring them.

The interior ministry said earlier this month that it had carried out crackdowns on illegal immigrants at more than 10,000 locations, including construction sites in Moscow.

Vladimir Putin overwhelmingly won the presidential election in March, and he will start his fifth term as president on May 7. He is apparently strengthening security measures because terrorist attacks could destabilize his administration.