WASHINGTON – President Donald Trump issued another tweeted threat to Iran on Wednesday, saying he would retaliate if the Tehran government struck again at U.S. interests in Iraq.

"Upon information and belief, Iran or its proxies are planning a sneak attack on U.S. troops and/or assets in Iraq," Trump tweeted. "If this happens, Iran will pay a very heavy price, indeed!"

Trump, who did not detail the plot, made the threat less than an hour after receiving a foreign intelligence briefing at the White House.

Later at a briefing, Trump said the intelligence indicating an attack was sound.

"We just have information that they were planning something and it’s very good information," Trump said.

He added: "We’re just saying don’t do it. Don’t do it. It'd be a very bad thing for them if they did."

Iranian-backed militias in Iraq continually threaten to attack U.S. and allied forces, according to a U.S. official who was not authorized to speak publicly. Threats arrive in a daily stream.

Some of the more visible threats have been issued by the Kataib Hezbollah militia, the group responsible for rocket attacks on U.S. bases in Iraq that have killed American troops and contractors.

One such attack, on March 11, killed two U.S. troops.

The militia recently posted a video called “Hunting Crows,” which shows rockets being fired at night and purports to be a training exercise for attacking U.S. troops, the source said. Another group has threatened that U.S. forces that arrive by air will be sent home dead.

Relations between the U.S. and Iran have been tense for decades, but especially in recent months.

In early January, Trump authorized a drone strike that killed a high-ranking Iranian general, Qassem Soleimani.

The strike was part of a tit-for-tat that included Iranian attacks on U.S.-backed Iraqi militias in Iraq. After Soleimani's death, the Iranians launched an airstrike on a military base in Iraq that housed several American troops, injuring many but not killing anyone.

The new threats come as both the United States and Iran battle the spread of the coronavirus pandemic.

More:Exclusive: Americans say Soleimani's killing made US less safe, Trump 'reckless' on Iran

The U.S. and Iran have also exchanged harsh words during the epidemic.

Even before the coronavirus, Iran's economy was being battered by U.S. sanctions. Officials in Tehran have criticized the U.S. for maintaining those sanctions in the face of the crisis.

Late last month, Secretary of State Mike Pompeo stated that Iran had refused American aid for addressing the coronavirus threat. At the same time, Pompeo criticized Iranian leader Ayatollah Ali Khamenei for spreading conspiracy theories that the United States caused the pandemic.

Trump did not explain what he meant by “information and belief” in a new Iranian plot, but analysts pointed out that those are legal phrases.

"'Information and belief' isn’t an intelligence term," tweeted attorney George Conway, the spouse of Trump adviser Kellyanne Conway. "It’s a phrase used in legal pleadings to make allegations, which is why Individual-1 is so familiar with it."