Iran's supreme leader Ayatollah Ali Khamenei on Friday insisted that the Islamic republic would "not back down" in the face of protesters who he called "vandals" and "saboteurs", in a speech broadcast on state TV.

Speaking to supporters in his first comments on the escalating protests since January 3, Khamenei said U.S. President Donald Trump's hands "are stained with the blood of more than a thousand Iranians" and predicted the "arrogant" U.S. leader would be "overthrown" like the imperial dynasty that ruled Iran up to the 1979 revolution.

Russia on Friday said the United States had decided to release two Russian members of the crew of a Russian-flagged oil tanker that Washington seized earlier this week.

"In response to our request, U.S. President Donald Trump has decided to release two Russian citizens aboard the Marinera tanker, previously detained by the United States during an operation in the North Atlantic," Russian foreign ministry spokeswoman Maria Zakharova said in a statement.

U.S. President Donald Trump said on Friday he cancelled a second wave of attacks on Venezuela after it began releasing "large numbers" of political prisoners this week.

"Venezuela is releasing large numbers of political prisoners as a sign of "Seeking Peace."... Because of this cooperation, I have cancelled the previously expected second Wave of Attacks," he said on his Truth platform.

Iranian protesters shouted and marched through the streets into Friday morning after a call by the country's exiled crown prince for demonstrations, despite Iran's theocracy cutting off the nation from the internet and international telephone calls.

Short online videos shared by activists purported to show protesters chanting against Iran's government around bonfires as debris littered the streets in the capital, Tehran, and other areas. Iranian state media broke its silence Friday over the protests, alleging "terrorist agents" of the U.S. and Israel set fires and sparked violence. It also said there were "casualties," without elaborating.

Russia said Friday it has used the new Oreshnik ballistic missile along with other weapons in a massive strike on Ukraine.

Ukrainian officials said four people were killed and at least 22 wounded in the capital overnight. Russia didn't say where Oreshnik hit, but Russian media and military bloggers said it targeted a huge underground natural gas storage facility in Ukraine's western Lviv region.

The Senate is expected to vote on a resolution Thursday that would limit President Donald Trump's ability to conduct further attacks against Venezuela, setting up a test for his expanding ambitions in the Western Hemisphere.

The war powers resolution would require Trump to get congressional approval before striking Venezuela again, and it comes after the U.S. military seized the president of the South American country, Nicolás Maduro, in a surprise nighttime raid and as Trump's administration is seeking to control Venezuela's oil resources and its government.

Denmark has welcomed a meeting with the U.S. next week to discuss President Donald Trump's renewed call for the strategic, mineral-rich Arctic island of Greenland to come under American control.

"This is the dialogue that is needed, as requested by the government together with the Greenlandic government," Danish Defense Minister Troels Lund Poulsen told Danish broadcaster DR on Thursday.

Guides who take tourists to enjoy the striking views of Sicily's Mount Etna are up in arms over tougher restrictions imposed by local authorities after a round of eruptions at the giant volcano in recent weeks.

Authorities in the city of Catania have suspended or restricted excursions to see the volcano's lava flows, prompting guides to go on strike for the first time in decades and leaving disgruntled tourists with fewer options to see the spectacle up close.

Iran does not want war with Israel or the United States, but is ready to fight back if attacked again, the country's foreign minister said Thursday.

Speaking upon arrival in Beirut, Abbas Araghchi told reporters that Iran is also ready for negotiations with the U.S. over its nuclear program as long as the talks are based on mutual respect rather than "dictation" by Washington.

U.S. forces have boarded a Venezuela-linked sanctioned oil tanker in the North Atlantic after pursuing it for weeks, a U.S. official said.

The official spoke to The Associated Press on Wednesday on the condition of anonymity to discuss sensitive military operations. The official said the U.S. military seized the vessel and handed over control to law enforcement officials.