The Pentagon is facing heat after it extended the deployment of National Guardsmen at the U.S. Capitol for another two months.

Lawmakers have amplified their calls to prove the validity of the Guards mission which earlier this week was extended through most of May as the Defense Department has struggled to relay the reasoning for the deployments months-long continuation.

Likely to add to the scrutiny is the Pentagons new estimate that the National Guards deployment at the U.S. Capitol is expected to cost $521 million through May.

The Guards additional two months will cost $111 million while the initial three months of the mission, from January to March, will cost an estimated $410 million, the National Guard Bureau said in a statement to The Hill on Friday.

Lawmakers from both parties in the House and Senate now want answers as to why the continued security is needed.

Top Senate Republicans on Friday demanded U.S. Capitol Police give justification for intrusive fencing and burdensome deployment of Guard troops at the Capitol, which they described as disproportionate to the available intelligence.

Our National Guard troops, who serve with great honor and distinction, are not law enforcement officers, and we will not abide the continued militarization of Capitol complex security, the senators wrote in a letter to U.S. Capitol Police Chief Yogananda Pittman.

Leaders of the House Armed Services Committee from both parties on Thursday said they were deeply troubled by the continued heavy military presence in the Beltway, calling instead for a drawdown.

We cannot ignore the financial costs associated with this prolonged deployment, nor can we turn a blind eye to the effects it will soon have on the National Guards overall readiness, Chairman Adam SmithDavid (Adam) Adam SmithOvernight Defense: Tucker Carlson comments cause military rage | Capitol guard duty questioned | Vet who served in Marine One unit charged in insurrectionHouse Armed Services leaders: Level of security at Capitol ‘not warranted at this time’Overnight Defense: Report urges sweeping changes to Capitol security | Biden touts female general nominees on International Women’s Day | US stands by Saudis after ‘heinous’ Houthi attacksMORE (D-Wash.) and ranking member Rep. Mike RogersMichael (Mike) Dennis RogersOvernight Defense: Tucker Carlson comments cause military rage | Capitol guard duty questioned | Vet who served in Marine One unit charged in insurrectionHouse Armed Services leaders: Level of security at Capitol ‘not warranted at this time’Lawmakers gird for spending battle over nuclear weaponsMORE (R-Ala.) said in a joint statement Thursday.

Senate GOP Leader Mitch McConnellAddison (Mitch) Mitchell McConnellThe Memo: Nation rallies for Biden on his COVID-19 responseSchumer vows quick Senate action on House gun reformsThe Hill’s Morning Report – Presented by the National Shooting Sports Foundation – House passes relief bill; Biden set for prime time addressMORE (Ky.), also weighed in Wednesday, calling the increased security overdone and an overreaction.

Im extremely uncomfortable with the fact that my constituents can’t come to the Capitol. With all this razor wire around the complex it reminds me of my last visit to Kabul, McConnell told reporters.

The Pentagon earlier this week approved a request from Capitol Police to extend the presence of nearly 2,300 guardsmen at the Capitol through May 23. That number is still roughly half of the 5,100 now stationed at the Capitol, with their deployment initially expected to end this Friday.

The deployment is down from a high of 26,000 following the Jan. 6 attack on the nations capital by supporters of former President TrumpDonald TrumpThe Memo: Nation rallies for Biden on his COVID-19 responseMaryland GOP governor applauds Biden after prime-time COVID-19 addressBiden denounces hate, violence against Asian Americans: ‘It must stop’ MORE looking to prevent Congress from certifying President BidenJoe BidenThe Memo: Nation rallies for Biden on his COVID-19 responseDemocrats debate fast-track for infrastructure packageJapanese prime minister expected to be Biden’s first foreign visit at White HouseMOREs victory in the November election.

The guardsmen were originally only meant to bulk up security for Bidens inauguration, but the deployment was extended afterward over continued security concerns.

I don’t think anybody wants to see this become an enduring mission, Pentagon press secretary John Kirby told reporters on Thursday, adding that there is a legitimate need for the Guard due to some capability gaps and capacity shortages right now that the Capitol Police are experiencing.

Kirby would not say, however, what threats were relayed from the Capitol Police when they asked for the extended mission.

Likewise, answers arent coming from the Capitol Police, who have yet to detail what dangers warranted the added two months.

Capitol Police last month suggested that extremists may be planning another attack on the building when President Biden delivers a joint address later this spring, something for which he has not yet set a date.

I havent been satisfied with any explanation Congress has received at numerous briefings that all these personnel, resources and barbed wire are needed, Senate Armed Services Committee ranking member Jim InhofeJames (Jim) Mountain InhofeOvernight Defense: Pentagon chief to press for Manchin’s support on Colin Kahl | House Dems seek to limit transfer of military-grade gear to policePentagon chief to press for Manchin’s support on key nomineeOvernight Defense: Capitol Police may ask National Guard to stay | Biden’s Pentagon policy nominee faces criticism | Naval Academy midshipmen moved to hotelsMORE (R-Okla.), complained in a statement last week.

Lawmakers and Washington, D.C., residents alike have chafed at the guardsmen prominently walking the halls of Congress and standing guard around security fencing across Capitol Hill.

The Capitol has also had to close off or restrict numerous hearing rooms, parking lots and other areas to allow Guard operations.

In addition to the high cost and ominous presence, the deployment has also faced a host of other problems, including the death of a National Guard member after a medical emergency, defense officials said Thursday.

Earlier this month, lawmakers in both parties expressed concern after roughly 50 guardsmen were sickened from undercooked food.

And in January, lawmakers were outraged after some guardsmen were forced to rest in a parking garage instead of inside the Capitol complex. After photos of them camped in the garage circulated online the troops were quickly moved back inside.

As the U.S. Capitol Police continues to build its personnel capacity, there is no doubt that some level of support from the National Guard should remain in the National Capital Region to respond to credible threats against the Capitol, Smith and Rogers wrote Thursday. However, the present security posture is not warranted at this time. … Its time for us to review what level of security is required, so [troops] can return home to their families and communities.  

Concerns over the ever-stretching deployment have also come from current and former defense officials.

In a memo to senior Pentagon officials last month, National Guard Bureau chief Gen. Daniel Hokanson said Guard officials were having difficulty finding enough volunteers to continue the mission.

And leaders from the National Guard Association of the United States on Friday released a statement saying it was increasingly difficult to convince Guard soldiers and airmen that their continued presence at the Capitol is warranted, after a year of unprecedented demand on the Guard thanks to the COVID-19 pandemic and several natural disasters.

National Guard soldiers and airmen here in Washington need to return home to their families, civilian employers and regular military obligations, NGAUS Chairman Maj. Gen. Michael McGuire and retired Brig. Gen. J. Roy Robinson, NGAUS president, said in the release.