From Washington, this is VOA news. I'm Larry London in Washington.

U.S. Defense Secretary Jim Mattis on a visit to Ukraine Thursday said Washington would keep up pressure on Russia over what he called "its aggressive behavior" and signaled his personal support for providing weapons to Kyiv.

"The U.S. and our allies will continue to press Russia to honor its Minsk commitments and our sanctions will remain in place until Moscow reverses the actions that triggered them.

As President Trump has made clear, the United States remains committed to diplomatic efforts to resolve the conflict in eastern Ukraine."

Mattis's visit, timed for Ukrainian Independence Day, is the second high profile show of U.S. support in as many months after U.S. Secretary of State Rex Tillerson came to Kyiv in July.

Ukraine has counted on U.S. support against Russia since a pro-Western government took power following street protests in 2014 when the Kremlin-backed president fled the country.

Hurricane Harvey is moving across the warm waters of the Gulf of Mexico heading toward the coast of Texas and strengthening as it goes.

U.S. meteorologists say the former tropical storm will be a major hurricane by the time it makes landfall late Friday. Peak winds will surpass 200 kilometers per hour when the hurricane hits a wide swath of coastline.

Hurricanes usually weaken rapidly once they move inland, but forecasters say this storm will follow an unusual pattern - stalling once it hits the coast, and then probably moving back out to sea briefly and making a second drenching pass at low-lying coastal communities.

Harvey is expected to pour at least 50 centimeters of rain over a wide area of the Texas coast.

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Just a week into talks to rewrite the North American Free Trade Agreement, President Donald Trump is already threatening to abandon the 23-year-old pact with Canada and Mexico.

At a high-profile campaign-style rally in Phoenix on Tuesday night, Trump predicted that the United States will probably end up terminating NAFTA at some point, though he said he hadn't made a final decision.

The prospect of reaching any diplomatic solution to the North Korean nuclear threat remains unclear as its leader Kim Jong Un has shown little willingness to compromise with adversaries in Washington or even engage with allies in Beijing.

State Department spokeswoman Heather Nauert on Thursday struck a slightly optimistic tone. "We consider it overall a good first step that there haven't been any missile launches or testing for three-plus weeks or so, but we need to see more."

After taking power in late 2011 following the death of his father Kim Jong [the second] Il, there were questions as to whether the young Western-educated North Korean leader would liberalize the longstanding repressive rule of his country, or whether he would be able to consolidate his grip on power.

A senior United Nations official warns some 20,000 civilians held hostage by Islamic State in the Syrian city of Raqqa are in great danger and everything possible must be done to help them escape. Lisa Schlein reports for VOA from Geneva.

The special adviser to the U.N. special envoy for Syria, Jan Egeland, Thursday said the needs of thousands of civilians trapped in five Raqqa neighborhoods under Islamic State control are beyond belief.

He says civilians are suffering large casualties from heavy shelling by the Syria government and the constant air raids by the U.S.-backed coalition forces.

"There seems to be no real escape for these civilians. I cannot think of a worse place on Earth now than in these five neighborhoods for these 20,000 people."

Egeland says the U.N. is urging the humanitarian task force, including members of the coalition fighting to retake Raqqa, to do whatever is possible to help people escape the embattled city.

Lisa Schlein, for VOA news, Geneva.

As climate change pushes ice further north each year, it is spurring talk of a gold rush in the Arctic for natural resources, shipping routes, tourism and fishing.

The Arctic, including the fabled northwest passage between the Atlantic and Pacific, is among earth's last largely unexplored regions. However, experts say many obstacles remain to reaping riches once blocked by ice.

Conservation is to pause large scale extraction of Arctic resources, fearing the fragile environment will be harmed.

I'm Larry London in Washington.

That's the latest world news from VOA.