Russian forces have destroyed Ukrainian drones targeting Moscow and its Black Sea Fleet, officials said, the latest in a surge of attacks on the capital and the flashpoint waterway.
Russia's defence ministry said its air force downed a Ukrainian drone over the capital at about 04:00 (0100 GMT) on Friday.
"The UAV, after being exposed to air defence weapons, changed its flight path and fell on a non-residential building in the Krasnopresnenskaya embankment area of Moscow," the ministry said on Telegram.
Moscow's mayor said emergency services were on the scene, but that early reports indicated there were no casualties.
"The wreckage of the UAV fell in the area of the Expo Centre, and did not cause significant damage to the building," Sergei Sobyanin said on Telegram.
State-run news agency TASS reported that one of the walls of the venue's pavilion had partially collapsed, citing emergency services.
"The area of the collapse is about 30 square meters (323 square feet)," emergency services told TASS.
TASS also reported that the airspace near the international airport of Vnukovo was briefly closed, with departures and arrivals delayed, citing the aviation service.
The expo centre, on the Krasnopresnenskaya embankment of the Moskva River, hosts regular exhibitions and trade shows, according to its website.
The venue is 100 metres (328 feet) from Moscow-City, an office block in the capital's main business district that was struck twice within days by debris from downed drone strikes this month.
Until a series of attacks in recent months, the capital had not been targeted during the conflict in Ukraine, which began more than a year ago.
Last week, Russia destroyed a Ukrainian drone over Moscow's west, with debris landing in a park on the Karamyshevskaya embankment.
In May drones were shot down near the Kremlin, less than five kilometres from the Expo Centre.
On July 30, Ukrainian President Volodymyr Zelensky warned that "war" was coming to Russia, with the country's "symbolic centres and military bases" becoming targets.
- Black Sea attack -
Hours before the strike on Moscow, Russia thwarted a Ukrainian marine drone attack on its warships in the Black Sea, the latest in a string of assaults on its fleet.
Russia's defence ministry said the drone was destroyed late on Thursday night by navy patrol ships, 237 km (147 miles) southwest of Sevastopol -- the base of its Black Sea Fleet on the Moscow-annexed Crimean peninsula.
Attacks from both sides have escalated in the Black Sea since Russia pulled out of a deal that had allowed safe export of Ukrainian grain through the shipping hub.
On August 4, Russia said it had repelled Ukraine's attempted drone attack on its Novorossiysknaval base in the sea, while a Ukrainian security source said the strike on a warship at the base was successful.
The attack came hours after a civilian cargo ship sailing through the Black Sea from Ukraine reached Istanbul in defiance of a Russian blockade.
Moscow announced last month that it would consider any ships nearing Ukraine in the Black Sea as potential military cargo carriers.
Ukrainian President Volodymyr Zelensky said the ship was using a "new humanitarian corridor" Kyiv established after the grain deal collapsed.
Days ago, a Russian navy ship fired warning shots and boarded a Turkish-owned but Palau-flagged cargo vessel that was sailing to a Ukrainian river port.
Russia has also ramped up attacks on Ukraine's port infrastructure in the Black Sea and the Danube River, a vital export route since the grain deal's scrapping, in recent weeks.
Russia's attempts to control shipping on the Black Sea come against the backdrop of a military counteroffensive launched in June by Ukrainian forces, which is supported by new Western equipment but making slow progress.
Russia detains US citizen suspected of spying
A Russian court has remanded a US citizen in custody on suspicion of spying, Russian media reported Thursday, the latest of a series of such cases.
Russian-born American, Gene Spector has pleaded guilty and reached a deal with investigators, Interfax reported, adding he faces up to 20 years in prison.
The state-run Ria Novosti news agency reported the case had been classified and no more details were known.
In September last year, Spector had already received a sentence of three-and-a-half years in prison for "corruption" in a case involving a former assistant to former Russian deputy prime minister Arkady Dvorkovich.
A first conviction in 2021 in the Spector case was overturned on appeal and sent back for reconsideration in July 2022.
According to TASS, Spector was born and raised in Russia before moving to the United States where he obtained citizenship. He was general director of Russia's Medpolimerprom company group.
Several US citizens have in recent years been handed heavy sentences in Russia. Washington accuses Moscow of seeking to use them as bargaining chips to obtain the release of Russians held in the United States.
In December last year US basketball player Brittney Griner was sentenced on drugs charges but freed shortly afterwards in exchange for Russian arms dealer Viktor Bout, held in the United State.
Wall Street Journal reporter Evan Gershkovich was detained last March on spying charges during a reporting trip to the Urals. He denies the charges.
Gershkovich, who continued reporting from Russia after the Kremlin launched its large-scale offensive in Ukraine, became the first Western journalist to be arrested and accused of spying since the Soviet era.