U.S. Secretary of State John Kerry said Tuesday he would visit Russia next week for the first time since taking office, with a host of issues including the war in Syria clouding bilateral ties.

His announcement came the day after President Barack Obama stepped up pressure on Moscow over Syria, telling Russian leader Vladimir Putin of his concern about the reported use of chemical weapons by the Damascus regime.

Russia's air transport agency on Tuesday banned all Russian civilian planes from flying through Syrian air space after the crew of a Russian passenger jet reported coming under threat over the war-torn country.

The federal agency Rosaviation said the ban on flights over Syria went into force on Monday and will remain until further notice.

Russia's two greatest art museums were engaged Tuesday in an unsightly public feud over an idea to revive a Moscow museum of Western art that was shut down by Stalin in the late 1940s.

The State Museum of New Western Art gathered the impressionist and early modern art collected by renowned Russian art collectors Sergei Shchukin and Ivan Morozov in the late Tsarist era.

U.S. President Barack Obama stepped up pressure on Russia over Syria on Monday, telling his Russian counterpart Vladimir Putin of his concern about the reported use of chemical weapons by the Damascus regime.

Obama also thanked Putin in the telephone call for his help after the Boston marathon bombings, and expressed condolences over a fire that killed 36 patients in a Russian psychiatric facility on Friday, the White House said.

Russian President Vladimir Putin will host his U.S. counterpart Barack Obama for a bilateral visit later this year as the two leaders pledged to intensify cooperation on Syria and counter- terrorism, a Kremlin aide said on Monday.

Putin's foreign policy aide Yury Ushakov said Obama had called Putin to discuss future contacts with the Russian leader including a bilateral visit just before the G20 summit that Russia hosts in Saint Petersburg in early September.

With technical support from Russia, Syria has bolstered its air defenses, posing a threat to U.S. aircraft if America decides to intervene in the war, a U.S. official said Monday.

The official confirmed a report that first appeared in the Wall Street Journal.

Unidentified assailants fired two land-to-air missiles at a Russian passenger plane carrying over 150 people when it flew over Syria on Monday, the Interfax news agency reported, citing an informed source in Moscow.

"The Syrian side informed us that on Monday morning unidentified people had fired two land-to-air missiles which exploded in the immediate proximity of a civilian plane belonging to a Russian airline," the source was quoted as saying.

Japanese Prime Minister Shinzo Abe and Russian President Vladimir Putin on Monday pledged to renew efforts to find a solution to a decades-long territorial row that has prevented the two sides from signing a World War II peace treaty.

After several hours of talks in the Kremlin, Abe and Putin agreed to order their foreign ministers to reopen talks on finding options for a solution that could be presented to the leaders.

Russia on Monday warned the West against using a search for weapons of mass destruction in Syria as an excuse for ousting President Bashar Assad along the lines of the notorious hunt for deadly arms in Saddam Hussein's Iraq.

Russian Foreign Minister Sergei Lavrov questioned why U.N. Secretary General Ban Ki-moon was calling for a fact-finding mission in Syria by citing unproven claims of the regime's use of chemical weapons in December.

Russian authorities secretly wiretapped the mother of the Boston bombing suspects and recorded her discussing jihad in vague terms during a 2011 telephone conversation, CNN reported Saturday.

The Russians only turned over the information to their U.S. counterparts in recent days, according to the report.