As the fighting in Gaza continues to intensify, the U.S. is increasingly becoming more involved — militarily and diplomatically — in three other hotspots in the Middle East, with fears growing that rising tensions could spiral into a much bigger war.

Why it matters: One of the Biden administration's main goals since the Oct. 7 Hamas terrorist attack has been to prevent the fighting in Gaza from spilling over to other parts of the region. But as time passes, this is becoming harder to achieve.

State of play: The U.S. has over the last three months sent dozens of Navy ships, hundreds of fighter jets and other aircraft, and thousands of soldiers to the Middle East in hopes of deterring Iranian-backed groups from launching attacks that could lead to a regional war.

• But tensions have continued to escalate across the region, particularly in the last month.

Iraq and Syria

Since Oct. 7, there have been more than 100 attacks by pro-Iranian militias against U.S. forces in Syria and Iraq, with the U.S. conducting several strikes in retaliation.

• The most recent incident took place in Baghdad on Thursday when the U.S. killed a leader of the Shiite militia Harakat al-Nujaba and one of his aides in an air strike.
• Pentagon Press Secretary Air Force Maj. Gen. Pat Ryder said on Thursday that the militia leader was involved in planning and conducting attacks against U.S. forces in the country.
• This was the most significant U.S. air strike since Oct. 7 — both because it was done in the Iraqi capital and because the target was a senior figure in Iraq. The strike increased tensions between the Biden administration and the Iraqi government, which denounced the U.S. attack.

Houthis and the Red Sea

Tensions are also rising in the Red Sea, where Yemen's Houthi rebels have attacked more than 25 commercial ships and U.S. Navy vessels since November, according to the Pentagon.

• The Houthi attacks have significantly hampered the freedom of navigation in one of the world's main commercial shipping routes and led to a rise in prices globally.
• U.S. officials said the Biden administration has been considering for several weeks taking military action against the Houthis, but President Biden has been hesitant to do so. That's in part because of concerns it could drag the U.S. further into the crisis militarily and fears it could hurt the Yemen peace process.
• Instead, the administration has focused on building an international coalition of countries and a multinational naval task force aimed at trying to deter the Houthis.

Since then, however, the situation has continued to escalate.

• A U.S. helicopter on Sunday fired on and sunk three Houthi boats that tried to attack a commercial ship, killing 10 members of the group.
• On Monday, Biden convened a call with his national security team to discuss the options against the Houthis, a U.S. official said. The U.S. and 12 other countries that are part of the international coalition later issued a statement warning the Houthis they will "bear the responsibility of the consequences" of any future attacks.
• A U.S. official who briefed reporters Wednesday declined to describe the statement as a red line or an ultimatum but said they "would not anticipate another warning."
• Still, the Houthis haven't appeared to be deterred. On Thursday morning, the militant group for the first time launched a one-way attack unmanned surface vessel in the Red Sea, Vice Adm. Brad Cooper said in a briefing. The missile didn't hit any ships, but it again deepened concerns.

Hezbollah and Lebanon

Tensions between Hezbollah and Israel along the Lebanon-Israel border continue to escalate, despite U.S. efforts to contain the situation. The assassination by Israel of senior Hamas official Saleh al-Arouri in Beirut earlier this week has heightened concerns even more.

• Biden envoy Amos Hochstein visited Tel Aviv on Thursday as part of an effort by the administration to find a diplomatic solution to calm down the situation.
• Israeli leaders told Hochstein they were willing to give a chance for a diplomatic solution, but stressed there's only "a short window of time" and they were ready to take military action to push Hezbollah farther away from the Israeli border — a step that could lead to an all-out war.

The big picture: Tehran has denied involvement in the recent attacks by its proxies.

• "Iran tries to ... pretend it has a hands-off posture when it comes to its proxies around the region, but that is not the way that we view it. I think the picture here is very clear," one U.S. official told reporters.
• The Biden administration has also said it will act forcefully to protect the American people and U.S. interests, but it has stressed it is wary of creating a situation that would drag the U.S. into the regional crisis even more.
• "We will act very forcefully when it comes to any threats against our people or our interests. We're also going to do so in a very smart way that does not potentially draw us in deep to a situation that actually plays into the hands of some of these proxy groups," the official said.

What to watch: Secretary of State Tony Blinken is scheduled to leave for the region later Thursday. He will visit several countries, including Israel, Qatar and Saudi Arabia, as well as the occupied West Bank.

• "He will discuss urgent mechanisms to stem violence, calm rhetoric and reduce regional tensions, including deterring Houthi attacks on commercial shipping in the Red Sea and avoiding escalation in Lebanon," the State Department said.

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