U.S. President Donald Trump says sanctions against Iran will not be lifted and will be tightened as long as they continue their threatening behavior, saying the Iranian regime has sought to reinforce its violence to escape sanctions by attacking vital facilities in Saudi Arabia.

Trump said in his speech to the UN General Assembly on Tuesday that his country's withdrawal from the nuclear deal with Iran came to prevent it from acquiring a nuclear weapon.

"We make it clear to our friends that they have to shoulder the burden of defending their security," Trump said, referring to Washington's allies.

On another issue, Trump urged Israel's neighbors to establish normal relations with it, noting that Iran's leaders last year considered Israel a cancer that must be removed and eliminated.

"We have spent more than $ 2.5 trillion and we have the most powerful army in the world and we hope we will not use it," he said.

On the Afghan issue, the US president said his administration was seeking to provide a brighter future for Afghanistan, "but the Taliban chose to continue its brutal attacks."

Business relations
President Trump said he hoped to sign a "wonderful" trade agreement with the UK after it leaves the European Union. "We will work closely with Prime Minister Boris Johnson on a wonderful trade agreement," he said.

In the context of trade relations with China, Trump has sharply criticized Beijing's practices, but has kept hope that the world's two largest economies may reach an agreement to end their trade dispute.

He said Beijing had "embraced an economic model based on huge market barriers, substantial government support, currency manipulation, forcible transfers of technology, intellectual property theft and large-scale trade secrets."