Pentagon leaders settled instead for a less-conspicuous operation: They sent the promised meals-ready-to-eat, or MREs, in commercial trucks from storehouses in Germany.
The episode illustrates the forces confronting the Obama administration as it tries to showcase its support for Ukraine's new leaders.
The U.S. doesn't want to embolden them to act more aggressively or give Russia a pretext to seize more Ukrainian territory, having already taken Crimea last month.
The same quandary is playing out again as the U.S. and the North Atlantic Treaty Organization struggle over how to reassure nervous allies in Eastern Europe without exacerbating the tension with Moscow.
The Supreme Allied Commander, U.S. Air Force Gen. Philip Breedlove, has submitted his recommendations for the alliance's military posture to NATO defense ministers, according to a spokesman.
The options for the U.S., according to U.S. officials briefed on the internal discussions, include expanding the number of F-16 fighters based in Poland to 18 from 12.
The U.S. could also temporarily position small units of up to 200 troops each from the Italy-based 173rd Infantry Division in Eastern European countries, and send a modest number of additional U.S. military planes to bases in the Baltic countries—Estonia, Latvia and Lithuania.
There are currently 10 F-15s in the Baltics, but their mission is due to end in May.
Pentagon officials play down the possibility of any larger troop deployments in countries bordering Russia, such as the Baltics.
That includes a mobilization of the 1st Brigade, 1st Cavalry Division, an Army unit based in Texas that is designated as the principal U.S. response force for NATO emergencies.
U.S. officials described the new steps as small by design to reduce the risk that Moscow will see the moves as a provocation and respond by, for example, seizing a strip of Ukrainian territory linking the Crimean peninsula to Russia.
U.S. intelligence agencies believe Moscow could launch such an operation without warning.
Ukrainian forces got the MREs late last month, about two weeks after requesting aid.
The White House says it is still reviewing other items on Kiev's wish-list, including medical kits, uniforms, boots and military socks.
"You want to calibrate your chest-thumps," a senior military official said of the step-by-step American response to Russian President Vladimir Putin's military moves.
"He does something else in Ukraine, we release the socks."
In addition to nonlethal gear including night-vision goggles, fuel, tires and body armor, Ukraine has asked the U.S. for small arms and ammunition, including up to 5,000 M16 assault rifles, U.S. defense officials said.
"We are still reviewing the Ukrainian requests to see what is appropriate for us to provide," said White House National Security Council spokeswoman Laura Lucas Magnuson.
"Our main focus continues to be on supporting Ukraine economically and diplomatically."
Another major Russian incursion into Ukraine could dramatically change the U.S.'s approach, a senior defense official said.
If that happens, then the administration would step up its actions, including consideration of moving larger numbers of American ground forces into Eastern Europe in defensive positions, one defense official said.
But the senior military official said even such a muscular deployment would have limited impact on Moscow's calculations.
"What is a brigade going to do against 40,000 Russian troops? Absolutely nothing," the official said.
In recent days, Russia has moved more elite forces near its border with Ukraine, including airborne units and special operations forces, according to U.S. officials.
U.S. intelligence agencies believe Moscow could seize a land bridge between Crimea and Russia—through Ukraine—to bring supplies into the newly annexed area.
U.S. officials believe the Russians are assessing various landscape features, from major roadways to rivers, which could define how much Ukrainian territory to take to create such a land bridge.
While U.S. intelligence agencies last week warned policy makers that another Russian military operation looked increasingly likely, officials don't think Mr. Putin intends to seize all of Ukraine.
Concern about Russia's motives was stirred by surveillance images released by NATO in Brussels on Thursday, showing temporary military bases close to the border.
Moscow claimed the images were out-of-date, prompting NATO officials Friday to release before-and-after photos it says prove there has been a recent buildup.
For instance, the new images depict overviews of a site at Belgorod, some 25 miles from the border.
A photo dated March 7 shows the site almost empty; by March 24, there is apparent evidence of a temporary base for ground forces, and helicopters.
The same is true at other sites, based on the before-and-after photos.
Gen. Breedlove on Thursday described a highly capable and alert Russian force.
But U.S. defense officials said U.S. and NATO options being outlined in coming days are nonetheless expected to reflect modest adjustments to force levels.
The Obama administration's delayed response to Ukraine's request for additional aid has raised concerns among some top American officials.
Defense Secretary Chuck Hagel and other advocates of a yes-or-no decision argue that the delay runs the risk of precipitating a Russian military move by raising doubts about U.S. intentions, the senior U.S. officials said.
In addition, officials are concerned that Washington's cautious response will sow doubts among Asian allies about the Obama administration's willingness to support them if they get into a skirmish with China over disputed territories.
Supporters of the administration's approach say that the caution shown by the White House may be working, noting that Russia has not carried out further military operations in Ukraine and has shown greater willingness to engage in negotiations with the U.S. and others about Ukraine's future.
Envoys from the U.S., Ukraine, Russia and European Union will meet in Geneva on Thursday to discuss ways of de-escalating the crisis.
Some policy makers argue that the proposed small U.S. deployments will have the intended effect.
"It doesn't take a big footprint to reassure allies," another senior U.S. official said.
In August 2008, in response to Russia's military offensive in Georgia, then-President George W. Bush ordered the Pentagon to send medical supplies and other aid using American air and naval forces.
The idea of delivering military food rations to Ukraine by U.S. military aircraft, originally developed by U.S. military officials in Europe, was nixed not only because of concerns about provoking Russia, but because of high costs.
But cautious U.S. military leaders also balked at an operation that would highlight America's role by using military planes or trucks.
Worried about how Russia would respond to images of U.S. military aircraft or vehicles arriving at Ukrainian bases, the Pentagon opted to use the civilian trucks, then announced the shipments in a simple news release.
"Optics are important," the senior military official said.
"But not too much."
Source: The Wall Street Journal