The US military called on Iraq's government on Tuesday to take steps to safeguard American troops in both Iraq and Syria after failed attacks a day earlier by Iran’s proxy militias.

The drone and rocket fire were the first such incidents since a near three-month pause in what had been almost daily attacks that culminated in the January killing of three US soldiers at the Tower 22 outpost in Jordan.

Meanwhile, the Biden administration on Tuesday announced criminal charges and sanctions against four Iranians over an alleged multi-year cyber campaign targeting more than one dozen American companies, the Treasury Department and the State Department said.

Sanctions were also announced against two companies, Mehrsam Andisheh Saz Nik and Dadeh Afzar Arman, that according to the Treasury Department employed the individual defendants and were front companies for Iran's Revolutionary Guard cyber command.

“The IRGC-CEC is one of the Iranian government organizations that has been responsible for, through a series of front companies, malicious cyber activity against the US and several other countries…The United States will not tolerate malicious cyber activities victimizing US companies,” the State Department said in a statement.

With US-Iran tensions soaring after the Jordan attack in January, and some calls from Republican lawmakers in Washington for a direct US response against Iran, a senior Iranian commander had called on militia to halt their attacks at the end of January.

The US retaliated against the attack in Jordan in early February, hitting multiple bases of Iranian proxies in Syria and Iraq,

Speaking at the Pentagon, Air Force Major General Patrick Ryder, a spokesperson, did not speculate about what triggered the renewal in attacks. But he called on Baghdad to act.

"These attacks put coalition and Iraqi personnel at risk. We call on the government of Iraq to take all necessary steps to ensure the safety of U.S. forces in Iraq and Syria against attacks from these groups," Ryder told a news briefing.

"If these attacks continue, we will not hesitate to defend our forces, as we have done in the past."

The US has some 2,500 troops in Iraq and 900 in eastern Syria on an advise-and-assist mission.

Although Washington has sanctioned many individuals and entities engaged in nefarious activities on Iran’s behalf, the Biden administration has not enforced the oil sanctions against Tehran, which is the main source of its income.

The United States helped Israel shoot down a massive wave of Iranian drone and missiles on April 14 fired by Tehran in retaliation for an April 1 Israeli strike against an Iranian diplomatic facility in Syria.

Washington has blamed Iran in the past for funding and directing militia in Iraq and Syria that attack US forces.

Iraqi Prime Minister Mohammed Shia al-Sudani, wary of his country becoming a battleground for fighting between the United States and Iran, met President Joe Biden earlier this month to turn a new page in US-Iraqi relations despite soaring regional tensions.

The US invaded Iraq in 2003 and toppled strongman leader Saddam Hussein, withdrawing in 2011 before returning in 2014 at the head of an international military coalition at the Baghdad government's request to help fight Islamic State insurgents.

With reporting by Reuters