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WASHINGTON (Reuters) - Republican U.S. senators plan to introduce legislation on Wednesday seeking to counteract what they see as Iran’s increasing influence in Iraq, amid concern about attacks in Iraq by groups U.S. officials consider Iranian proxies, a Senate aide said on Wednesday.

Among other things, the bill, whose text was seen by Reuters, would impose terrorism-related sanctions on Iranian-controlled militias and require the U.S. Secretary of State to publish and maintain a list of armed groups receiving assistance from the Iranian Revolutionary Guard Corps, or IRGC.

Sponsors of the “Iranian Proxies Terrorist Sanctions Act” include Senators David Perdue, Ted Cruz and Marco Rubio. A similar bill, backed by Republican Representative Ted Poe, has been introduced in the House of Representatives.

There was no immediate word on when the legislation might be considered by congressional committees, normally the first steps toward becoming law.

Three mortar shells landed inside Baghdad’s heavily fortified Green Zone just after midnight local time on Friday, the first such attack in several years in the area, which houses parliament, government buildings and many foreign embassies.

On Tuesday, the United States warned Iran that it would “respond swiftly and decisively” to any attacks by its allies in Iraq that resulted in injury to Americans or damage to U.S. facilities.

Reuters reported last month that Iran had given ballistic missiles to Shi’ite Muslim proxy groups in Iraq and was developing the capacity to build more there, a development likely to exacerbate tensions between Tehran and Washington, already heightened by President Donald Trump.

In May, Trump withdrew the United States from a 2015 international nuclear accord with Iran and ordered the reimposition of U.S. sanctions suspended under the deal aimed at stalling Tehran’s nuclear capabilities.

Iran’s Sunni Muslim Gulf neighbors and its arch-enemy Israel have expressed concerns about Tehran’s regional activities as a threat to their security.