The U.S. military conducted airstrikes on two facilities in eastern Syria on Thursday in response to ongoing attacks against American military personnel in Iraq and Syria over the past week, according to the Department of Defense.

A pair of F-16s targeted two facilities – a weapons depot and an ammo storage area – near Abu Kamal used by Iran's Islamic Revolutionary Guard Corps and affiliated groups, a senior U.S. defense official told Fox News' Jennifer Griffin. It's unclear if there were any Iranian militants at the facilities when they were hit.

Defense Secretary Lloyd Austin said in a statement Thursday night that the U.S. does not seek conflict, but the "Iranian-backed attacks" on American forces are "unacceptable and must stop."

"Iran wants to hide its hand and deny its role in these attacks against our forces. We will not let them," Austin said. "If attacks by Iran’s proxies against U.S. forces continue, we will not hesitate to take further necessary measures to protect our people."

IRAN-BACKED MILITIAS IN IRAQ CLAIM RESPONSIBILITY FOR ATTACK ON US MILITARY BASE IN SYRIA

There have been 19 attacks against American personnel in Iraq and Syria since Oct. 17, including three additional attacks on Thursday, according to Pentagon spokesperson Brig. Gen. Pat Ryder. 

A U.S. contractor died from a cardiac incident while sheltering in place during the attacks and 21 American troops were injured – all of whom have since returned to duty, Austin said.

DRONE STRIKES TARGET US MILITARY BASES IN SYRIA, IRAQ AS REGIONAL TENSIONS FROM ISRAEL-HAMAS WAR ESCALATE

U.S. officials made clear the strikes were conducted solely in response to the attacks against American personnel and are not connected to the Israel-Hamas war.

"They are separate and distinct from the ongoing conflict between Israel and Hamas, and do not constitute a shift in our approach to the Israel-Hamas conflict," Austin said. "We continue to urge all state and non-state entities not to take action that would escalate into a broader regional conflict."

A senior U.S. defense official also said Israel was not informed of the plan ahead of the airstrikes.

The White House has not yet addressed the airstrikes, but Austin said in his statement that President Biden has "no higher priority than the safety of U.S. personnel."

"[Biden] directed today’s action to make clear that the United States will not tolerate such attacks and will defend itself, its personnel, and its interests," Austin said.

A senior U.S. defense official reiterated those sentiments during a briefing Thursday night and said American forces are "ready to do it again, for deterrence."

The U.S. military boasts a strong presence in the Middle East in efforts to deter additional attacks in the region.

As of Wednesday, the USS Dwight D. Eisenhower Carrier Strike Group, the USS Gerald R. Ford Carrier Strike Group, the USS Mount Whitney, destroyer USS Carney, the USS Carter Hall, the USS Bataan and the USS Mesa Verde are all present in the surrounding waters.

There have also been 900 troops deployed to the Middle East, according to Ryder on Thursday, in addition to the thousands of troops already stationed in the region.

Fox News' Liz Friden and Jennifer Griffin contributed to this report.

This is a developing story. Check back for updates.

Rep. Dean Phillips of Minnesota is jumping into the 2024 White House race with a long-shot Democratic primary challenge against President Biden.

The campaign launch by the millionaire businessman and co-founder of a gelato company turned three-term House Democrat comes as the 80-year-old president continues to suffer from underwater approval ratings among many Americans and faces serious concerns over his physical and mental stamina.

Phillips filed paperwork with the Federal Election Commission on Thursday to officially set up his presidential campaign, and his website www.dean24.com went live in the evening.

"I am excited to announce my candidacy for President in 2024. It’s time to put our country back together again – and use our differences to make us stronger. It’s time to repair America," Phillips said in a launch video posted on social media on Thursday evening.

BIDEN BREAKS CENTURY OLD TRADITION AS HE FORGOES FILING FOR THE PRIMARY IN THIS STATE

And when asked in an interview with CBS News if he's running for president, the 54-year-old Phillips answered "I am. I have to." The recorded interview is scheduled to be broadcast Friday morning.

Friday morning is also when Phillips, who represents a congressional district in suburban Minneapolis, will formally declare his candidacy in New Hampshire, the state that for a century's held the first primary in the presidential nominating calendar.

Phillips, one of the wealthiest members of Congress, is scheduled to hold a campaign launch event outside the New Hampshire Statehouse in Concord. And Phillips will enter the Statehouse and file at the Secretary of State's office to place his name on the New Hampshire's presidential primary ballot.

A bus decorated with "Dean Phillips for President" was headed to New Hampshire earlier in the week, and is expected to take the candidate on a tour.

Phillips, citing the president's age, has repeatedly criticized Biden for "not passing the torch" to the next generation of Democratic leaders and urged that a serious primary contender challenge the president for the party's 2024 nomination.

CHECK OUT THE LATEST FOX NEWS 2024 PRESIDENTIAL ELECTION POLLING

When no other Democrats considered running against Biden, Phillips began to consider himself for the mission. Earlier this month, he told MPR (Minnesota Public Radio) News that "it’s healthy to have alternatives. I think voters are demanding it."

And in his CBS News interview, Phillips pointed to recent polling suggesting that former President Donald Trump is edging Biden in hypothetical 2024 general election matchups.

"I think President Biden has done a spectacular job for our country," Phillips said. "But it's not about the past. This is an election about the future."

While the president is the commanding front-runner for his party’s 2024 nomination, polls indicate Biden faces mounting concerns from Democrats over his age. Those surveys also suggest that many Americans - including plenty of Democrats - don't want the president to seek a second term in the White House.

The White House, when asked earlier this week about Phillip's expected candidacy, pointed to the lawmaker's "almost 100% support of this president."

Phillips — who recently stepped away from his leadership role as co-chair of the Democratic Policy and Communications Committee due to his potential White House bid — let lapse a September deadline he set for himself to decide whether he would launch a primary challenge against the president. And last week he missed a deadline to place his name on the ballot in Nevada, which is holding its presidential primary on Feb. 6 in the Democratic Party's nominating calendar.

According to the Democratic National Committee (DNC), which earlier this year upended years of tradition by revamping their longstanding nominating calendar, Nevada's supposed to vote second, along with New Hampshire, three days after South Carolina’s Feb. 3 kickoff primary. 

NEW HAMPSHIRE'S SUNUNU SAYS 2024 RACE IS ‘WIDE OPEN’ IN FIRST PRIMARY STATE

The revised scheduled was initially proposed by Biden, who came in a disappointing fifth in the 2020 New Hampshire primary before rebounding in Nevada and South Carolina enroute to winning the nomination and eventually the presidency.

But New Hampshire's on course move up the date of its primary to late January, in accordance with a state law that mandates the Granite State's presidential primary is held seven days ahead of a similar contest.

With New Hampshire to hold what is certain to be a primary that’s out of compliance with the DNC's revamped 2024 nominating calendar, Biden is avoiding the unsanctioned contest.

And on Tuesday, the president's 2024 re-election campaign announced that Biden would not file to place his name on New Hampshire's ballot. Top Democrats in the state now plan to mount a write-in effort on behalf of the president.

But there are concerns that anger among Granite Staters to the move by Biden and the DNC to revamp the nominating calendar, and the president's absence from the primary ballot, could serve as another distraction for Biden as he marches towards re-nomination.

Longtime New Hampshire Democratic Party chair Ray Buckley, who recently took a call from Phillips, told Fox News that "both polling and grassroots interactions in New Hampshire reveal a high level of support for President Biden among the likely voters."

"It would be a tough challenge for Phillips or anyone. But sure, c’mon on up!," Buckley says he told Phillips.

The president is already facing a long-shot primary challenge from best-selling author spiritual adviser Marianne Williamson, who is making her second straight White House run.

Biden was also facing an uphill primary challenge from environmental lawyer and high-profile vaccine critic Robert F. Kennedy Jr., who is a scion of arguably the nation’s most famous family political dynasty.

But Kennedy announced at a campaign event in Philadelphia earlier this month that he would seek the White House as an independent candidate.

The DNC is fully backing Biden, as the president campaigns for re-election. At its winter meeting in February, the DNC unanimously passed a resolution committing its "full and complete support" for the re-election of Biden and Vice President Kamala Harris. Additionally, it has said there will be no primary debates between Biden and any of his challengers.

Williamson, Kennedy and others in the party criticized the DNC and Biden, but there is political precedent for the move. No incumbent president has participated in primary debates in modern times. 

Jim Demers, a longtime New Hampshire-based political consultant and lobbyist who is helping to lead the write-in effort for Biden, terms a primary challenge by Phillips "a ridiculous idea."

"Democrats in New Hampshire support the president," Demers told Fox News. "So if his mission is to divide Democrats and help [former President] Donald Trump, then that’s what he’s doing."

Fox News' Kellianne Jones and Deirdre Heavey contributed to this report

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