The United States has positioned two aircraft carrier battle groups in the Middle East, deployed more missile defenses to the region, and evacuated nonessential personnel from its embassy in Iraq as Iranian-backed proxy forces have targeted U.S. troops in Syria and Iranian-backed Hezbollah militants have attacked Israeli forces across the northern border with Lebanon.

“Recently, we've seen rocket and UAV attacks against bases housing our troops in Iraq and Syria. We're concerned about potential escalation,” Defense Secretary Lloyd Austin said on ABC on Sunday. “In fact, what we're seeing is a prospect of a significant escalation of attacks on our troops and our people throughout the region.”

On Saturday, Austin ordered an unspecified number of additional forces to “prepare to deploy” in what he called “prudent contingency planning to increase their readiness and ability to quickly respond as required.”

At a briefing last week, the Pentagon confirmed a series of drone attacks in Syria, including one that caused minor injuries at the At-Tanf garrison where U.S. troops are based, as well as an incident in which the guided-missile destroyer USS Carney, operating in the Northern Red Sea, shot down three cruise missiles and several drones that were launched by Houthi forces in Yemen.

The deployment of the additional U.S. assets is meant to send a clear message, Secretary of State Antony Blinken said on CBS. “No one should take advantage of this moment to escalate, to further attacks on Israel, or for that matter attacks on us, on our personnel.

The State Department has issued a “worldwide caution alert” advising U.S. citizens overseas to “exercise increased caution because of increased tensions around the world and the potential for terrorist attacks, demonstrations, or violent actions against U.S. citizens and interests.”

The cross-border attacks by Hezbollah are fueling fears of the war widening to include a second front along Israel’s northern border with Lebanon.

On Sunday, retired Gen. Jack Keane, former Army vice chief of staff, said that so far, Hezbollah has not fully mobilized or evacuated its own citizens from the border, but it is still the “No. 1 threat.”

“They're a paramilitary force. They have conventional capability. They have 130,000-plus rockets and missiles that the Iranians have given them,” Keane said on Fox News Sunday. “They have a significant capability. Israelis have handled them before but struggled with it back in 2006. What we would see here is a very heavy rocket and missile attack that can range all of the major cities.”

“But the only thing that is relevant here, so our viewers understand, it's Iran,” Keane said. “They will make those decisions, whether they go or not. And that likely has something to do with how things go in Gaza with the Israelis and what the perception is in the international community as well. It's going to be Iran's decision, just as the Hamas attack on Israel was Iran's decision.”

MOST SERIOUS CHALLENGE SINCE WWII

“The United States is facing global security challenges we haven't seen since World War II,” Keane said. “We have three geographic areas of vital national interests, Europe, China and Indo-Pacific region, and also in the Middle East. War has broken out in two of those areas, and the third area, China, he's threatening it.”

“This is not happening by accident. They perceive that we don't have the capabilities to deter them anymore, that we've lost some political will. And here, we're reflecting this loss of political will in Ukraine,” Keane said. “The world is becoming a more dangerous place. And the United States's weakness is what they perceived. Whether it's real or not is not — it's irrelevant. They perceived it.”

“This is a dangerous world. And it demands world leadership,” former Defense Secretary Leon Panetta agreed in an interview on CNN. “And it demands world leadership. … If the United States doesn't provide that leadership, very frankly nobody else will.”

“We're reflecting this loss of political will in Ukraine,” Keane said. “We not only have to support Ukraine — Ukraine's got to win this war. It's related to these other two regions. … We cannot have Russia win that war. If that happens, China wins, and so do the Iranians.”