More than half a million Americans woke up without power Tuesday, as freezing temperatures gripped swathes of the country in a monster storm that has killed at least 30 people.

A frigid, life-threatening Arctic air mass could delay recovery as municipalities from New Mexico to Maine tried to dig out following the storm, which dropped a vicious cocktail of heavy snow and wind, along with freezing rain and sleet.

A U.S. naval strike force led by an aircraft carrier was in Middle Eastern waters on Tuesday as Iran vowed to hit back against any strike and President Donald Trump said he believed the Islamic republic still wanted talks.

Washington has not ruled out new military intervention against Tehran over its crackdown on protests, which according to rights groups saw thousands of people killed within days.

China promised on Tuesday to provide Cuba with "support and assistance" in the face of repeated threats from the United State, which weeks ago removed Havana's ally in Venezuela Nicolas Maduro.

Beijing and Havana are longtime socialist allies, and Chinese authorities have consistently opposed the economic blockade imposed on the island for decades by the United States.

Russian forces killed six people and wounded dozens of others, including two children and a pregnant woman, in attacks on Ukraine's energy facilities, Kyiv announced Tuesday.

President Volodymyr Zelensky said the latest bombardment undermined peace efforts and urged allies to step up pressure on Moscow to end the war, which is grinding towards its fourth anniversary.

Three people were killed on Monday in Israeli strikes -- one in the southern city of Tyre and two later in Kfar Rumman near the city of Nabatiyeh.

Hezbollah's Al-Manar television said the Tyre strike killed Sheikh Ali Noureddine, "who previously worked at Al-Manar channel as a presenter of religious programs".

Damascus thwarted on Monday an attempt to smuggle weapons into Lebanon, state media reported, days after Israel struck several border crossings between the two countries, saying they were used by Hezbollah.

The official SANA news agency said security forces intercepted the shipment in a car in the Bureij area, near the border with Lebanon.

Hezbollah chief Sheikh Naim Qassem said Monday that Hezbollah will not remain “neutral” should Iran come under a new attack, but added that it would choose whether to intervene or not at the appropriate time.

“When (U.S. President Donald) Trump threatens (Iran’s supreme leader) Imam (Ali) Khamenei, he is threatening tens of millions who follow this leader,” Qassem said via video link during a Hezbollah rally in solidarity with Iran.

Nearly 3.8 billion people could face extreme heat by 2050 and while tropical countries will bear the brunt cooler regions will also need to adapt, scientists said Monday.

Demand for cooling will "drastically" increase in giant countries like Brazil, Indonesia and Nigeria, where hundreds of millions of people lack air conditioning or other means of beating the heat.

More than 1,000 people were evacuated in Sicily after a four-kilometer (2.5-mile) section of cliff crumbled during a storm, leaving houses perched perilously on the edge, authorities said on Monday.

Land was continuing to give way due to rain that has soaked the area in recent days, said the mayor of the southern hill town of Niscemi.

The United Arab Emirates will not allow attacks on Iran to be launched from its territory, the foreign ministry said in a statement on Monday.

Last week, President Donald Trump said a U.S. "armada" was heading toward the Gulf and that Washington was watching Iran closely after a bloody crackdown on protesters.