Although President Joe Biden bluntly declared that "we need a cease-fire now" in Lebanon, his administration appeared to subdue its messaging on a push for a temporary truce between Israel and Hezbollah, as U.S. officials on Monday acknowledged Israel intends to scale up operations in Lebanon.

"Military pressure can, at times, enable diplomacy," State Department spokesperson Matthew Miller said. "Of course, military pressure can also lead to miscalculation. It can lead to unintended consequences, and we're in conversations with Israel about all these factors now."

The shift in tone comes as the administration has acknowledged Israel has communicated plans to conduct what officials described as "limited" ground incursions into Lebanon aimed at taking out Hezbollah infrastructure -- a follow-up to its major aerial attacks over the last several days, including one that killed the militant group's leader, Hassan Nasrallah.

It also coincides with the State Department's public admission that it has again hit a wall in its efforts to push forward a cease-fire in Gaza because Hamas has refused to engage with Egyptian and Qatari mediators for weeks, leaving the Biden administration unable to pull together what senior U.S. officials advertised as a "final" proposal for a deal.

"We can't get a clear answer from Hamas of what they're willing to entertain and what they're not willing to entertain," Miller said.

Over the course of nearly a year, these two fronts of conflict sparked by Hamas' Oct. 7 attack on Israel have exasperated U.S. diplomats who have sought to prevent war from engulfing the entire Middle East.

"The Biden team is definitely frustrated, but in many ways, it's a frustration born largely out of its own wishful thinking and unwillingness to face some harsh realities in today's Middle East," Brian Katulis, a senior fellow for U.S. foreign policy at the Middle East Institute, told ABC News.

Katulis argued that Iran -- a chief supporter of both Hezbollah and Hamas -- and Israel's right-wing government have been edging toward a regional war, and that the Biden administration "lacks the will and strategic focus to fundamentally shift those dynamics."

"The U.S. is trapped in a reactive, crisis-management mode because it remains unwilling to use the force and leverage needed to produce the diplomatic outcomes it says it wants to achieve," he said. "Darker days are ahead."

Israel sees few benefits to curbing its military campaign in Lebanon, as it has already successfully eliminated several of its top targets and made progress toward restoring security on its northern border.

U.S officials say the Israeli government views a diplomatic alternative -- a 21-day cease-fire backed by the Biden administration, France and several other countries -- as counterproductive to its aim of allowing Israelis that have been displaced by Hezbollah's near-constant stream of rocket fire to return to their homes as quickly as possible.

And while many have been wary about provoking Iran, some Biden administration officials and experts now see Tehran as increasingly unlikely to fully enter the fray.

"Iran's options range from bad to worse against Israel, given its conventional military deficiencies and the blows its regional terror network has endured," Behnam Taleblu, a senior fellow at the Washington-based Foundation for Defense of Democracies, told ABC News.

Taleblu added that Tehran now appears likely to change course and take action only if it perceives the threat posed by Israel to be "existential and to the homeland."

But even if the conflict in the Middle East doesn't expand further, White House officials had hoped a negotiated truce between Israel and Hezbollah could resuscitate Gaza peace talks.

Jon Alterman, director of the Middle East Program at the Center for Strategic and International Studies and a former State Department official, warned that the administration must worry that continued deadlock will weaken U.S. influence in the Middle East and beyond.

But he said there's still an opportunity to make progress -- if the Biden administration can reign in Israeli Prime Minister Benjamin Netanyahu.

"All wars are much easier to start than end, though, and it is not clear whether Netanyahu, his sharply divided cabinet or his ruling coalition have any idea how they might do that," Alterman said. "He will need a broad, U.S.-led coalition to push him, and it needs to start coming together now."