Japan is leasing the Philippines five military surveillance aircraft to better help them patrol sea lanes in the highly contested . Manila already received two of the Beechcraft TC-90 planes, which will be a boost to its limited patrol capabilities. The move is significant because both countries are navigating complex territorial maritime disputes with China.

The Beechcraft TC-90 is a twin-turboprop plane, based on the civilian Beechcraft King Air C90 and currently used to train train Japanese Self Defense Force pilots. Much faster and with double the range of the Philippines’ current Navy planes, the TC-90 can also be fitted with basic surface and air surveillance radar. The lease was secured under former Philippines president Benigno Aquino III and has been in the works for some time.

It may not sound like much, but as notes, the Philippines has one of Asia’s weakest militaries. For Japan, it will mark the first time the country has loaned military aircraft to a foreign nation after dropping its self-imposed ban on weapons exports in 2014. It also signals Japan’s growing defense cooperation with the Philippines. While the U.S. has long had a defense treaty with the Philippines, Japan, arguably the most powerful country in the region behind China, is an equally important partner.

To contain China’s expansionism, Manila will have to establish key regional defense partnerships and Japan is one of them.

The Philippines has long complained about Beijing’s encroachment on its territorial waters in the South China Sea, as I have . Last summer, an international tribunal ruled that China violated the Philippines’ territorial integrity by building artificial islands in its waters. Beijing refuses to honor the ruling.

Japan, which has no claim to the South China Sea, does have a dispute with Beijing over disputed islands in the East China Sea. Brunei, Malaysia, Taiwan and Vietnam also have disputes with China over the area.

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Philippines President Rodrigo Duterte—who, it should be noted, even if his military is comparably weak—is walking a very fine line in his attempt to balance a conciliatory stance with Beijing while protecting his country’s sovereignty. Recently, he said he is willing to share resources with China in disputed waters because he can’t stop the country from building on a shoal near the Philippines’ western coast, according to ; China seized the shoal in 2012.

Missing in this conversation is the U.S.’ updated South China Sea policy. So far, the only words coming out of the White House on the subject is bluster—and, in advisor Steve Bannon’s case, radio broadcasts from 2016 in which he goes on unhinged diatribes predicting a war with China, as previously reported. In January, then- secretary of state nominee Rex Tillerson the U.S. would not allow it to access islands it build in the South China Sea. Beijing responded calmly by warning the incoming administration not to engage in destabilizing rhetoric. The Trump administration has shown no public signs that it is crafting a vision of how it plans manage the complex circumstances of America’s allies in the region against the expansionism of China, a shared nemesis.

Also unknown is the White House’s view of Duterte himself, a man who once cursed Obama and, consequently, forced him to a meeting the two were supposed to hold. All the while, China shows no signs of slowing its encroaching ways in the South China Sea and the U.S. appears to be M.I.A.

Tokyo is playing its expected role by strengthening its military ties with Manila, but the Duterte administration will need far more than five surveillance aircraft to keep Beijing at bay. Some practical U.S. engagement with this longtime ally to back up all of its anti-China bluster would certainly help.