The Biden administration's "over-the-horizon" strategy in Afghanistan is drawing serious questions from lawmakers and counterterrorism experts, as the U.S. withdrawal shifts calculations on threats and capabilities, Axios' Jonathan Swan and Zachary Basu report.

Driving the news: Tensions ramped up in an Aug. 27 conference call between President Biden's top national security officials and senators from both parties, sources familiar with the discussions tell Axios.

The big picture: Critics tell Axios that Biden and his team have yet to provide sufficiently detailed plans or explanations about their counterterrorism strategy to lawmakers conducting oversight.

Pentagon press secretary John Kirby said in a statement to Axios:  “While we won’t speak to details of our discussions with members of Congress or about internal deliberations, we absolutely maintain the capability to conduct over-the-horizon strikes against threats that may threaten the homeland or our interests."

Behind the scenes: About 1pm on Aug. 27 — the day after the Kabul airport bombing that killed 13 American service members and dozens of Afghan civilians — some of Biden's top national security officials held a conference call with senators from both parties.

• Briefers included Secretary of State Blinken, deputy secretary of Defense Kathleen Hicks, Homeland Security Secretary Alejandro Mayorkas and vice chairman of the Joint Chiefs of Staff Gen. John Hyten, according to three sources on the call.
• The sources, one who read aloud from notes taken during the call, said the conversation grew especially heated when Senate Minority Leader Mitch McConnell asked: "Given the fuel poured on the fire of terrorism, what are your plans to conduct the war on terrorism? ... Even though we seem to have given up, they [the terrorists] have not."

Colin Kahl, the undersecretary of Defense for policy, told McConnell, "What's left of al-Qaeda does not pose an imminent threat to the homeland," according to the notes shared with Axios. That account was confirmed by two other sources.

• "We have repositioned forces to the Gulf to provide an indicator and warning. We maintain strike aircraft and authorities to do so. We must maintain vigilance to the threat in Afghanistan, Yemen, Somalia and elsewhere." The Biden team then moved on to the next question.
• Republicans on the call said they were frustrated by the answer and what they saw as Kahl's dismissiveness, given the rapidly deteriorating security environment in Afghanistan and what had turned out to be incorrect recent assurances from the administration about the situation on the ground there.

The White House declined to comment on details of the Aug. 27 briefing.

• The National Security Council directed Axios to a speech on the administration's broader counterterrorism strategy delivered by Homeland Security adviser Elizabeth Sherwood-Randall last week.

Even before the call, lawmakers were raising questions, Jonathan and Zachary report.

The so-called over-the-horizon capabilities Biden has repeatedly touted make identifying and striking terrorists with aerial surveillance and drones launched from outside the country the linchpin of America's post-withdrawal counterterrorism strategy.

• But in every country where the U.S. has deployed elements of a so-called over-the-horizon strategy, like in Yemen, Somalia, or Iraq and Syria, it's had an intelligence network, a nearby air base and some form of local partner on the ground.
• In Taliban-controlled Afghanistan — where the CIA has evacuated its sources, the nearest air bases are in the Gulf, and the local security partner is an FBI-wanted terrorist — it has none.

What they're saying: On Aug. 26, Senate Intelligence Vice Chairman Marco Rubio (R-Fla.) and two fellow committee members, Sens. Ben Sasse (R-Neb.) and Roy Blunt (R-Mo.), sent Biden a letter demanding to know how the U.S. will rebuild lost intelligence and counterterrorism capabilities.

• Said Sen. Lindsey Graham (R-S.C.): "If over-the-horizon worked, there'd be no ISIS in Iraq and Syria. We were told the same thing then. …"

Between the lines: It's not just Republican lawmakers who are skeptical.

• Gen. Frank McKenzie, who leads U.S. Central Command, told Congress in April: "I don’t want to make [over-the-horizon] sound easy. It’s going to be extremely difficult to do it, but it will not be impossible."
• Seth Jones, a CT expert at the Center for Strategic and International Studies, said it's "absolutely unrealistic" to think an over-the-horizon strategy could be sufficient for anything more than "pinprick strikes."

A Democratic aide on the House Foreign Affairs Committee pointed to an Aug. 27 drone strike in Afghanistan's Nangarhar Province, which the Pentagon says killed two ISIS militants, as an example of how over-the-horizon can be effective.

• But two days later, another drone strike killed 10 civilians after overhead surveillance mistook water canisters for explosives, according to a New York Times investigation.

The Pentagon's John Kirby told Axios: "As Secretary Austin said, there isn’t a part of the earth we can’t reach if required, and we do not always need a presence on the ground to effectively strike. It is more difficult, to be sure, but it is not impossible — as we have proven in other places."

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Secretary of State Antony Blinken can expect the most aggressive questioning of his career when he testifies tomorrow before the House Foreign Affairs Committee and on Tuesday in Senate Foreign Relations, Jonathan and Zachary report.

Why it matters: Republicans see the hearings as their first chance to directly confront a top-ranking Biden official about the chaotic U.S. withdrawal from Afghanistan.

• Democrats see it as a moment in which they must reject GOP efforts to blame Biden for 20 years of bipartisan mistakes.

Republicans say they'll demand to know exactly how many Americans and allies remain stranded in Afghanistan, following the latest evacuations and persistent obstacles — and how specifically the U.S. plans to get them out.

• They want to know the specific breakdown and vetting for those who've gotten out. They'll raise concerns about criminals or terrorists being evacuated, "child-bride" trafficking and Taliban fighters using U.S. gear left behind that was supposed to be "demilitarized."

The other side: Democrats will point to the peace deal the previous administration negotiated with the Taliban and cite Donald Trump's own boast in June: "I started the process, all the troops are coming home. [Biden] couldn’t stop the process."

• One Democratic source told Axios that Republicans "are making this as much of a Benghazi as they possibly can."

For the record: State Department spokesman Ned Price said Blinken "has prioritized engagement with Congress from his first days" in office, including in recent Afghanistan briefings and calls.

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The Senate has confirmed just two of Biden's ambassadorial nominations, far behind the 56 confirmed envoys President Obama had at this stage, Axios' Hans Nichols reports from data compiled by the Partnership for Public Service.

• Just one in four other national security positions at the Pentagon and Departments of Justice and State are filled.
• That compares with 57% of positions filled at the time of the Sept. 11 attacks in 2001.

What's happening: Sen. Ted Cruz (R-Texas) has been preventing most ambassadors from moving to the floor for a vote.

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The next few weeks will be crucial to enacting Biden's agenda — and determining how Democrats perform in next year's midterms, Axios' Sarah Mucha and Alayna Treene report:

• Tomorrow and Tuesday: Several House committees will drop big chunks of Biden's $3.5 trillion spending package and continue to mark up the bill in a series of legislative marathons.
• Wednesday: Senate Majority Leader Chuck Schumer set this as a "soft" deadline for the Democrat-run committees to complete drafting their portions of the budget bill. It seems unlikely we'll have the full bill by then.
• Saturday: Supporters of jailed Jan. 6 rioters will hold a "Justice for J6" rally on Capitol Hill. House Speaker Nancy Pelosi will host the "Big 4" congressional leaders in her office tomorrow morning for a security briefing from Capitol Police chief Tom Manger.

Sept. 30: The federal government runs out of money. Pelosi and House Majority Leader Steny Hoyer said during a Friday caucus call that the House will consider a short-term spending bill when the chamber returns on Sept. 20.

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Dana Bash's back-to-back interviews with Sen. Joe Manchin (D-W.Va.) and Budget Committee Chair Bernie Sanders (I-Vt.) this morning on CNN tell you everything you need to know about how far apart these key Democrats remain on the $3.5 trillion reconciliation package and infrastructure spending.

• Remember: In a 50-50 Senate, Democrats must be unanimous for their plan to pass, Alayna reports. But Manchin wants to spend no more than $1.5 trillion.

Watch the interviews here and here.