Pleading for a repeal of a law that strictly limits defense spending, a panel of four-star military officers warned lawmakers Tuesday that the fiscal constraints are crippling the military's ability to respond to threats around the world.

Appearing before the House Armed Services Committee, the officers delivered a message that appears to grow grimmer each time it's delivered. It echoed President Donald Trump who promised to reinvest in a "depleted" military although annual defense spending is more than $600 billion.

"You've been lacking a little equipment, we're going to load it up. You're going to get a lot of equipment," Trump said at Central Command on Monday.

Each of the military services have delivered to Congress plans for increasing the 2017 defense budget by more than $30 billion to acquire new jet fighters, armored vehicles, improved training and more. The informal proposals, obtained by The Associated Press, represent the first attempt by Trump's Defense Department to halt the erosion of the military's combat readiness. The shortfalls outlined in the documents may provide Trump and the national security hawks in Congress with a powerful incentive to strike the caps on military spending.

Adm. William Moran, the vice chief of naval operations, says more than half of all Navy aircraft are grounded because they're awaiting maintenance or lack needed spare parts. The figure is even higher for the service's front line F/A-18 fighter jets, according to Moran.

Gen. Daniel Allyn, the Army's vice chief of staff, told the panel that only three of the Army's more than 50 brigade combat teams have all the troops, training and equipment needed to fight at a moment's notice.

Portions of the plans will likely be included in the formal supplemental budget for 2017 that the Trump administration is sending to Capitol Hill soon.

The Marine Corps, arguing for a $4.2 billion boost to its 2017 budget, warned that the "nation's force in readiness" will have to continue shifting money intended for new weapons to pay current bills.

"As near-peer competitors probe the limits of American retrenchment and the operational environment grows more complex, the Marine Corps of today is largely optimized for the past and sacrificing modernization to sustain current readiness," the service's budget amendment reads.

The Navy's request totals $12 billion in additional spending and asks for 24 F/A-18E/F Super Hornet fighters, one San Antonio-class amphibious landing dock ship, and dozens more Sidewinder missiles.

Without more money, the 2017 fiscal year — which ends Sept. 30 — "is projected to have a significant shortfall in afloat readiness," according to the Navy document.

The Budget Control Act of 2011 set limits on how much could be spent on defense through 2021 while exempting money provided for overseas warfighting operations. Between 2011 and 2014, the Pentagon's budget fell by more than $100 billion. Across-the-board spending limits known in Washington-speak as sequestration were triggered in 2013, forcing reductions that led to widespread concern the military services would be unprepared to fight the nation's wars.

The Bipartisan Budget Act of 2015 provided temporary relief from the cuts, but unless the law is changed the limits will return in the 2018 budget year and would force defense budgets to levels far lower than the Pentagon says are prudent. If the budget caps are breached, automatic spending reductions would be triggered. Money provided for warfighting operations is exempt from the caps.

That prospect unnerves the top Pentagon brass. Gen. Stephen Wilson, the vice chief of staff of the Air Force, told the committee the service's "advantage over potential adversaries is shrinking." Wilson said the average Air Force aircraft is 27 years old and more than half of the inventory would qualify for antique vehicle license plates in the state of Virginia.

The Republican chairmen of the House and Senate Armed Services Committees, Rep. Mac Thornberry of Texas and Sen. John McCain of Arizona, are pushing for a base military budget of $640 billion in 2018 — a nearly $100 billion increase over the amount authorized for the 2017 fiscal year. Thornberry says Republican plans to rein in federal spending in other areas, such as Medicare and Medicaid, and overhauling the tax code will generate savings that can be funneled into defense.

But the push to dramatically increase defense spending could run into stiff resistance from fiscal conservatives, who have argued any budget savings should be used for deficit reduction. The picture will get even murkier if Trump holds to his campaign pledge to reduce taxes and protect entitlement programs from cuts. Democrats, meanwhile, will demand dollar-for-dollar hikes for domestic programs, further complicating efforts to add tens of billions of dollars in military spending.