The US Air Force has begun grounding about a third of its combat aircraft in response to deep budget cuts that began to take effect in March.
The move will affect units in the US, Europe and the Pacific.
Air Force Gen Mike Hostage said aircraft would be grounded on a "rotating basis" to focus on "fulfilling critical missions".
Separately, the US Navy has said cuts force it to ground its Blue Angels air show team for the rest of the year.
The Air Force's budget for the fiscal year ending in October is being reduced by $591m (£386m).
The cuts are part of the series of deficit reduction measures that began to take effect on 1 March.
About $85bn in across-the-board cuts for this year are divided roughly in half between military and domestic programmes.
The cuts took effect after Democrats and Republicans failed to agree to another plan to cut spending and reduce the US budget deficit.
The Pentagon had previously announced layoffs of 46,000 temporary employees in response to the budget pressures.'Risk' to airpower
The Air Force says the aircraft stand-down is the result of cuts to the Air Combat Command's operations and maintenance account. The budget cuts have forced the service to reduce its flying by about 45,000 training hours.
Some affected units will stand down after current deployments, but the first units will be grounded on Tuesday 9 April.
A combat command spokesman said the Air Force will shift those units' focus to ground-based training exercises to maintain basic skills and aircraft knowledge.
Exceptions would be made for aircraft about to deploy to Afghanistan, as well as those poised to respond in North Africa, including Mali, Gen Philip Breedlove, commander of US Air Forces, said in March.
"The current situation means we're accepting the risk that combat airpower may not be ready to respond immediately to new contingencies as they occur,'' Gen Hostage said in a statement on Tuesday.
Here's a list of the grounded units via
The Aviationist: 94th Fighter Squadron - Grounded April 9
27th Fighter Squadron - Basic mission capable through September
3rd Fighter Wing - Two squadrons combat ready mission through September
15th Wing - One squadron combat mission ready through September
49th Wing - One squadron combat mission ready through September
F-15 C / D
67th Fighter Squadron - Basic mission capable through September
44th Fighter Squadron - Basic mission capable through July, then Combat mission-ready through September
48th Fighter Wing - One squadron combat mission ready through September
F-15E
336th Fighter Squadron - Grounded April 9
335th Fighter Squadron - Combat mission-ready through September
48th Fighter Wing - Two squadrons stand down April 9
391st Fighter Squadron - Stands down April 9
F-16 C / D
8th Fighter Wing - Two squadrons combat ready mission through September
77th Fighter Squadron - Stands down April 9
55th Fighter Squadron - Combat mission-ready through September
79th Fighter Squadron - Basic mission capable through July, then combat mission ready through September
555th Fighter Squadron - Stands down April 9
510th Fighter Squadron - Combat mission-ready through September
13th Fighter Squadron - Combat mission-ready through September
14th Fighter Squadron - Basic mission capable through September
51st Wing - One squadron combat mission ready through September
57th Wing - One squadron (Thunderbirds) stands down April 9
158th Fighter Wing - One squadron stands down April 9
169th Fighter Wing - One squadron stands down April 9
187th Fighter Wing - One squadron stands down April 9
354th Fighter Wing - One squadron stands down April 9
4th Fighter Squadron - Basic mission capable until redeployment
421st Fighter Squadron - Basic mission capable through September
A-10C
75th Fighter Squadron - Basic mission capable through July, then combat mission ready through September
51st Wing - One squadron combat mission ready through September
52nd Fighter Wing - Closing
442nd Fighter Wing - One squadron stands down April 9
917th Wing - One squadron stands down April 9
HH-60G
18th Wing - One squadron combat mission ready through September
48th Fighter Wing - One squadron combat mission ready through September
B-1B
7th Bomb Wing - One squadron combat mission ready through September
2nd Bomb Wing - Two squadrons stand down April 9
B-2
509th Bomb Wing - Two squadrons combat ready mission through September
B-52
2nd Bomb Wing - One squadron stand down April 9
5th Bomb Wing - Two squadrons combat ready combat mission through September
E-3B/C/G
2nd Bomb Wing - Basic mission capable through September
18th Wing - One squadron basic mission capable through September
552nd Air Control Wing - One squadron basic mission capable through September
SE-4B
55th Wing - One squadron combat mission ready through September
EC-130H
55th Electronic Combat Group - One squadron combat mission ready through September
OC-135B
55th Wing - One squadron combat mission ready through September
RC-135S
55th Wing - One squadron combat mission ready through September
RC-135U
55th Wing - One squadron combat mission ready through September
RC-135V / W
55th Wing - One squadron basic mission capable through September
TC-135W
55th Wing (training) - One squadron basic mission capable through September
WC-135C / W
55th Wing. - One squadron combat mission ready through September