The Air Force is preparing to move a special operations squadron of 10 CV-22 Ospreys to a base in Japan, where they will be on the frontlines of the United States' mounting standoff with China and North Korea.

The first three tilt-rotor aircraft are expected to arrive at Yokota Air Base, just west of Tokyo, in the second half of 2017, with another seven arriving by 2021, according to officials at the Pentagon.

Flown by Air Force Special Operations Command, the Ospreys will provide increased capability for special operators to respond to crises in or near Japan. The Air Force also uses Ospreys for combat search-and-rescue missions and to respond to natural disasters.

In addition, the Osprey squadron will "increase interoperability" and strengthen relationships with the Japan Self-Defense Forces, the department said in a statement.

Air Force officials recently announced that they are haven’t discussed many of the details of the plan, saying only that it is relocating 46 civilian employees and their families who now reside on the base to make way for Osprey squadron facilities and for an additional 1,100 airmen.Yokota Air Base in Fussa, Japan, just west of Tokyo.

The key airlift hub for the Western Pacific already is home to 11,500 personnel and more than 20 aircraft with the 374th Airlift Wing and the 36th Airlift Squadron, including a number of C-130H Hercules, C-12s and UH-1s. It is also home to the headquarters of 5th Air Force, with its frontline air bases spanning Japan from north to south. Soon, it also will house a squadron of CV-22 Ospreys, which the Air Force uses for special operations and combat search and rescue missions..

The civilian relocation appears to be step one of a larger plan to boost the number of aircraft and personnel at the strategically located facility.

Yokota is within striking distance of two countries that have rattled Washington in recent months: China and North Korea. And the Air Force said it expects to send additional airmen and aircraft to the base in the near future, though it has not specified exactly what units or platforms might be going.

The moves comes at a time when key U.S. allies are scrambling to contain an assertive China and an unpredictable North Korea. U.S. forces are also returning to the Philippines in greater numbers, part of the Obama administration’s focus on the Asia-Pacific region. All of this comes at a time when key U.S. allies are scrambling to contain an assertive China and an unpredictable North Korea.

"For the past five years this has been official Obama administration policy/grand strategy," said Michael O'Hanlon a senior fellow with the Brookings Institution, a think tank in Washington, D.C. "2016 is obviously Obama's last year to leave a mark, and I think he'd want to keep momentum going."

Not all of the new forces are a direct response to security threats, O'Hanlon said.

"We're going to constantly be modernizing forces in the Pacific," he said. "We would be doing that even if there was no China or North Korea."

The airmen are likely to find themselves involved in disaster-relief efforts, multinational training, and counter-terrorism operations. But, O'Hanlon added, "it's pretty clear China is a driving impedance."

On April 16, the Air Force announced it was sending a new air contingent to Clark Air Base in the Philippines. The group, which consists of three HH-60G Pave Hawk helicopters and five A-10 Thunderbolt IIs, has already begun flying maritime surveillance missions.

"Putting those aircraft there right now is a little bit of a message, because it's not like we've had that kind of offensive airpower there before," O'Hanlon said. "The A-10, in theory, could be used against the Abu Sayyaf [insurgent] movement. In practice, I don't believe even that's the case. I think the A-10 is designed to give us loiter capability around the Scarborough Shoal."

The shoal,  is an area roughly 130 miles off the west coast of the Philippines, that was often used by Filipino fishermen. But Chinese naval forces have largely seized control of the territory and prevented Filipino boats from gaining access. Moreover, they have recently been observed surveying the area, raising fears that they may be considering building have  In one of their first missions, four A-10s and two HH-60s of the Philippine air contingent conducted a flying mission through international airspace in the vicinity of Scarborough Shoal, providing air and maritime situational awareness, according to the Air Force.

If the Air Force chooses to send other aircraft to the region in the future — such as the F-22 Raptor — O’Hanlon said it would be an even more direct message to China, O’Hanlon said.

"The F-22 would have no relevance except for dealing with a high-end threat like China," he said.

Squadrons of F-22s — the Air Force’s most advanced air superiority fighter — are now deployed have currently been conducting tours around Europe, in a reassuring ance mission to allies and sending a message to Russia. F-22s in the Pacific theater could largely perform the same role, O’Hanlon said. In fact, F-22s and B-52s flew show-of-force missions over the Korean Peninsula early this year in response to North Korea's sabre rattling.

Tensions are also running high further to the south.

China has claimed most of the South China Sea as its territorial waters — a large stretch of the Pacific Ocean bordered by China and Taiwan in the north, the Philippines to the east, Malaysia and Indonesia to the south, and Vietnam and Thailand to the west.

The Chinese military has been building a series of man-made islands in the Spratly Islands chain, drawing anger from its nearby neighbors. The U.S. has several times sent Navy ships to travel through the region in an effort to show it still considers the region to be international waters.

On April 16, the Air Force announced it was sending a new air contingent to Clark Air Base in the Philippines. The group, which consists of three HH-60G Pave Hawk helicopters and five A-10 Thunderbolt IIs, has already begun flying maritime surveillance missions.

"Putting those aircraft there right now is a little bit of a message, because it's not like we've had that kind of offensive airpower there before," O'Hanlon said. "The A-10, in theory, could be used against the Abu Sayyaf [insurgent] movement. In practice, I don't believe even that's the case. I think the A-10 is designed to give us loiter capability around the Scarborough Shoal."

The shoal,  is an area roughly 130 miles off the west coast of the Philippines, that was often used by Filipino fishermen. But Chinese naval forces have largely seized control of the territory and prevented Filipino boats from gaining access. Moreover, they have recently been observed surveying the area, raising fears that they may be considering building man-made islands there as well.

In one of their first missions, four A-10s and two HH-60s of the Philippine air contingent conducted a flying mission through international airspace in the vicinity of Scarborough Shoal, providing air and maritime situational awareness, according to the Air Force.

China has claimed most of the South China Sea as its territorial waters — a large stretch of the Pacific Ocean bordered by China and Taiwan in the north, the Philippines to the east, Malaysia and Indonesia to the south, and Vietnam and Thailand to the west.

The Chinese military has also started building a series of man-made islands in the Spratly Islands chain, drawing anger from its nearby neighbors. The U.S. has several times sent Navy ships to travel through the region in an effort to show it still considers the region to be international waters.

The U.S. Navy and Air Force responses to its territorial claims have brought diplomatic protests from China, and on Friday that nation denied the U.S. aircraft carrier John C. Stennis entry for a stopover at Hong Kong.

Zack Cooper, a fellow with the Center for Strategic and International Studies in Washington, D.C., said the naval and air power is partially to show American commitment to the region.

"Obviously pressure has been going on, both in the Korean peninsula and in the South China Sea," he said. "I think many countries in the region are looking for a demonstration of U.S. resolve to remain engaged."

He noted that the A-10s sent to Clark are reported to have already started flying maritime awareness missions in the vicinity of the Scarborough Shoal.

Pacific Air Command has said only that the A-10s have completed two missions in conjunction with Philippine air forces.

CSIS recently published a report with 28 recommendations the U.S. can take in the Pacific. Among the suggestions was spreading out bases and assets throughout the region.

"As you know, the U.S. is highly reliant on a small number of bases. Those are increasingly vulnerable to attack," Cooper said.

That was part of the reasoning behind the 2014 Enhanced Defense Cooperation Agreement between the U.S. and the Philippines that allows the U.S. military to set up more bases on the island nation.

"The trend is towards the U.S. putting more of its forces forward in the region, in part because it takes less time to reach a location if a contingency occurs," Cooper said.

Who exactly controls the South China Sea is currently being debated by a United Nations tribunal at The Hague in the Netherlands. The Philippines has filed several territorial claims in the international court over Chinese naval activity and construction on near-by reefs. But Chinese leaders have indicated they do not believe the dispute should be settled by a foreign court far away from Southeast Asia.

"The Chinese have disputed whether that court of arbitration actually has any jurisdiction in this matter," Cooper said. "I think the reality is, if you read the United Nations convention on the law of the sea, it's quite clear that the permanent court decision is binding, regardless of what the Chinese say."

As for North Korea, that nation has appeared undeterred by sanctions and threats over its nuclear program, and seems poised to conduct its fifth nuclear test.

On Thursday, the North Koreans launched two ballistic missiles, though both appeared to be failures and crashed seconds after launch, reports said.

The move brought swift international criticism, with U.N. Secretary-General Ban Ki-moon urging the isolated Communist nation to stop taking such provocative actions.

"Clearly North Korea is going to be belligerent regardless of what the United States does," Cooper said. "I'm not sure putting more forces in the region is going to cause the North Koreans to do anything more aggressive than what they were already going to do."

And as for those civilians at Yokota who are being moved to make way for the Ospreys, Col. Douglas DeLaMater, the commander of the 374th Airlift Wing, said the civilians have 60 days from April 13 to find new accommodations.

"I understand this is unwelcomed news," he said in a letter sent to base civilians. "These upcoming changes are great news for Yokota and the Air Force, but unfortunately require civilians who have resided in non-surplus housing for more than five years – a very small percentage of civilians living on base – to vacate their quarters to make way for new applicants."

The civilian employees can move into surplus housing on the base that isn't receiving regular maintenance, or they can relocate off base at the expense of the 374th Airlift Wing. Those living off base will receive a housing stipend from the government. Any civilians schedule to leave the base anyway in 2016 are being exempted from having to move.