WASHINGTON — The U.S. military's top brass warned lawmakers Wednesday it will mean lost lives, halted training and sidelined equipment if Congress punts on spending legislation for this year and forces the military to operate for the next five months under fiscal 2016 levels.

Lawmakers must finalize a budget for the remainder of fiscal 2017 by the end of April or trigger a partial government shutdown. In recent days, talk of a continuing resolution to fund the government through the end of September has slowly built in the halls of Congress, raising concerns among defense officials who say that would cause tremendous funding headaches for the military.

Army Chief of Staff Gen. Mark Milley warned that with the U.S. facing foreign threats and wars against terrorism, it is no time to risk national security by closing the year with a continuing resolution or returning to statutory budget caps.

"It will do just that, it will increase risk to the nation and ultimately result in dead Americans on a future battlefield," Milley said of both. "Lack of 2017 appropriations and no supplemental increase in funding will significantly impact readiness and increase the risk to our force."

On Wednesday, the military service chiefs appeared before the House Armed Services Committee to paint a dire picture of their services, each stretched thin and weary from the cumulative effect of eight years of unpredictable funding and fights around the globe. 

The service chiefs also stumped for President Donald Trump's immediate request for a $30-billion boost. But despite Republican support in the House and Senate for the plan, passage of the budget boost remains problematic given Democratic opposition because it violates automatic spending caps and cuts billions from non-defense spending.

Air Force Chief of Staff Gen. David Goldfein warned that the service's active-duty fighter pilot shortage would exceed 1,000 by the end of the fiscal year. Without funding, only squadrons in or heading to a fight will train, he said.

"It takes 10 years and $10 million to train a fighter pilot, and 1,000 short equates to $1 billion in capitol investment that walked out the door," Goldfein said.

To boot, a CR would negate authorized pilot bonuses and keep 2,000 recruits from training until an appropriations bill is passed, Goldfein said. "They have given up jobs, left home, made plans, all to be told they have to wait months to pursue their dreams," he said.

As the military has grappled with funding shortfalls, the chiefs said, it has seen competitors like Russia, China and North Korea continue apace, and U.S. armed forces were jolted in 2014 when Russia annexed Crimea and it was called to combat the Islamic State group.  

When Rep. Susan Davis, D-Calif., suggested ow budget gridlock had the new normal, bristled, equating it "professional malpractice."​ 

"The world is more dangerous by the day," Milley said. "Pass a budget."

The Army would have gaps in readiness, armor, air defense, artillery, aviation and training resource gaps, and it would defer plans to double brigade combat teams — from three to six. It would also halt basic and other training when money stops in July, Milley said.

"If we don't get this supplemental passed, Fort Jackson and many others would come to a screeching halt," Milley said. "The impact will be across all the services, it be very dramatic, very significant, and it's something that must be avoided."

The Navy would have to realign $4.4 billion to execute planned ship purchases, meaning late deliveries. It would also be forced to find more than $500 million to shift to pay raises, housing allowances and other cost-of-living adjustments for sailors.

Richardson worried the unpredictability would drive away valued personnel. "I'm competing every day with the public sector, and the pool of qualified people with the skills is smaller, and it gets smaller every time someone gets hired by another place," he said.

The Air Force would halt efforts to grow end strength, undercut efforts to shore up maintenance and defer bonus repayments used to retain airmen. The service would see a $2.4 billion shortfall in readiness accounts, a $1 billion hit in weapon system sustainment, and a halt to all restoration and modernization efforts.

The CR would impact 60 new start programs, limit munitions production, and force delays to the new MQ-9 upgrades, Joint Interagency Combined Space Operations Center and C-130H Avionics Modernization Program Increment 2.

Under a CR, the Marine Corps would be unable to counter enemy drones; halt flight operations in July; delay construct of an amphibious ship; and delay modifications for 200 Maverick missiles, procurement of 100 Hellfire missiles and recovery of laser Joint Direct Attack Munition stocks. Marines would also be unable to participate in several large-scale exercises.

The Marines would cut the following platforms: Joint Light Tactical Vehicles (74 vehicles), Common Aviation Command and Control System (10 systems), RQ-21 unmanned aircraft systems (1 full system, which includes ground infrastructure plus five air vehicles), the F-35B (1 aircraft) and the CH-53K (2 aircraft).

House Armed Services Committee Chairman Rep. Mac Thornberry, R-Texas, repeated his pledge not to approve a long-term continuing resolution for the military.

"The most important thing now is to repair the damage," Thornberry said. "We have the chance to begin doing so by passing a full appropriations bill for this year, acting favorably on the supplemental request, and then enacting adequate authorization and appropriations for fiscal year 2018."

The committee's lead Democrat, Rep. Adam Smith of Washington, said he opposed passage of defense appropriations without the rest of the federal budget and that he favors a reexamination the scope of the Defense Department in light of the funding available.

"I do not believe the answer is to continue to expand what we want those tasks and responsibilities to be, and we kind of hope that we somehow come up with the money to meet them," Smith said. "Because the tasks and responsibilities that have been described by the president, what he wants the military to do — he sent up a $603 billion military budget, and that doesn't even come close."

Among Democrats' objections to the 2017 supplemental appropriations bill that Trump sent to Congress is the $5 billion request in new funding to combat ISIS without a promised accompanying new strategy for that fight.

In a testy exchange, Rep. John Garamendi, D-Calif., asked whether the chiefs expected Congress to approve the funding without the plan, and Milley refused to discuss "a classified plan" and referred Garamendi to Defense Secretary Jim Mattis and the president.

House lawmakers have already passed a fiscal 2017 defense appropriations measure, and Senate Appropriations Defense Subcommittee Chairman Thad Cochran, R-Miss., said on Tuesday there were "a lot" of issues to be resolved before lawmakers can reach a bipartisan deal to fund the government.

That subcommittee's ranking member, Sen. Dick Durbin, D-Ill., said a Senate defense appropriations bill — which is ready to go, save for a single issue — would be the legislative vehicle for a larger deal.

"We've been ready to go," Durbin said. "I hope we're going to be the anchor for the package."

Leo Shane III contributed to this report.