St. Petersburg was shaken by an explosion that tore through a metro train
on Monday, leaving at least 10 people dead and dozens injured.
The attack occurred as Putin was visiting the city to address a media forum and meet the Belarusian President Alexander Lukashenko.
Putin began the meeting by expressing his condolences to the victims and said investigators are considering all potential causes of the blast. "Naturally, we always consider all options -- both domestic and criminal, primarily incidents of a terrorist nature."
Prime Minister Dmitry Medvedev called the explosion a "terrorist attack," while head of the Russian Federation Council's defense committee Viktor Ozerov said it was no coincidence that St. Petersburg was chosen to carry out the attacks.
"The choice of the place and the timing of these blasts is not accidental, the president of Russia is in [Saint Petersburg], the media forum is taking place there, there are many journalists," Ozerov told Russian news service Sputnik.
Heartland of the Russian state
The symbolism of attacking St. Petersburg -- the heartland of the Russian state and the hometown of Putin, Medvedev and other Kremlin officials -- comes at a moment of heightened security and sociopolitical concerns in Russia, according to former CNN Moscow bureau chief Jill Dougherty.
Putin's tight grip on a burgeoning insurgency in the south has essentially squashed all terrorist attacks in Chechnya, a republic in southwestern Russia.
But one of Putin's grave concerns is the thousands of Russians -- many of them believed to be Chechens -- who Putin says
are fighting alongside ISIS in Syria. Putin has warned they could be returning home to carry out attacks on Russian soil.
Steve Hall, former CIA Chief of Russia Operations, believes Russian counter-terrorism teams will be looking into whether Chechen and Russian rebels were involved.
"Russia has a terrorist problem, although there is some controversy as to what the political nature is," Hall told CNN.
An opportunity for US-Russia dialogue?
The attack's aftermath may provide a strategic political opportunity for the US and Russia, Dougherty told CNN.
US President Donald Trump has previously called for cooperation with Russia in the fight against Islamic terrorism, which may be an attractive offer to Putin.
If the investigation confirms that jihadists were behind the attack, one potential side effect could be closer intelligence sharing between Russia and the US in the fight against ISIS and other terror groups, Peter Truscott, author of "Putin's Progress" and "Russia First" told CNN.
Attack comes after nationwide protests
The attacks also come at a time of domestic political upheaval -- anti-corruption demonstrations have been held in Moscow and dozens of other cities across Russia over the past two weeks, with thousands of Russians taking to the streets
to protest against corruption.
Putin admitted last Thursday that Russia has a problem with state corruption but -- citing the Arab Spring -- warned of the dangers to Russian society if law and order broke down.
"This is relevant, and we are working on it, " Putin said, adding, "The only thing that I think is wrong is for certain political forces to try to use this in their own interests, for self-promotion in the political arena ahead of political events such as elections rather than to improve the situation."
The attack will likely result in increased security measures across Russia, potentially giving a boost to Putin in the lead-up to the the 2018 election campaign, Dougherty said.