US troops already have a small but significant footprint in the Philippines. US special forces have spent the past 12 years in the southern part of the country helping Philippine troops battle Abu Sayyaf and Jemaah Islamiah, Islamic groups with links to al-Qaeda. US troops also participate in frequent military exercises with the Philippine military.

Since President Barack Obama announced his so-called "pivot to Asia", however, the United States has been pushing for greater access to Philippine bases and the right to build exclusive facilities on them - a politically contentious issue that crippled negotiations last October.

The stakes are high: the Philippines needs an ally in its territorial disputes with China, which have been steadily worsening, and the Philippines' century-long military and political relationship with the US makes it a key component of Obama's military rebalancing plans in Asia.

"A failed agreement would send the alliance back to the stone ages," says Ernest Bowers, a senior adviser at the Centre for Strategic and International Studies in Washington, D.C.

But five rounds of talks have yielded little progress on that front. Now, as negotiators are sitting down for a sixth and purportedly final round of negotiations this week, the American response to Haiyan looms large.

"The massive relief operation conducted after Haiyan gave the executive branch a really basic rationale for US military presence - that [the Philippine] armed forces simply don't have the capability for disaster response," says Renato De Castro, a professor of international studies at De La Salle University in Manila.

There's more pressure than ever to reach an agreement ahead of Obama's trip to the Philippines in April. But the issue remains a sensitive one. The Philippine legislature ousted US forces from the country in 1991 over issues of national sovereignty and the public's perception that American troops were above the law, after soldiers were accused of rape and human rights abuses.

Now Philippine law prohibits any foreign military from keeping bases on the islands, although the two countries maintained a strong military relationship. They have drafted new agreements that allow them to work together on Philippine soil without violating current law. At times, this has meant the sharing of military facilities, while carefully ensuring that the Philippine armed forces retain full control of their own bases.

An expanded US military presence, the argument goes, would benefit both sides by bringing substantial humanitarian resources closer to where they are needed, while also having American forces in the area in case of a Chinese provocation in the South China Sea.

"As we are seeing in the Philippines today, our military presence in the region is vital, not only to deter threats and defend allies, but also to provide speedy humanitarian assistance and unmatched disaster response," US National Security Adviser Susan Rice said in November.

More importantly, the decision to shift US military capabilities into the Philippines - and towards the region more broadly - lines up with the Obama administration's highly touted pivot to Asia.

But past talks have floundered on two main points. While the Philippines has agreed to allow the US military to use and build facilities on Philippine bases, it also insists on full access to those facilities, something the US is loathe to provide.

Meanwhile, the US wants a longer-term agreement that will outlive President Benigno Aquino's term in office, a move that would require approval from the Philippine legislature and may pose a political challenge.

But intense military jockeying in the region, and Philippine fears of a direct confrontation with China, may very well have made the talks' outcome a foregone conclusion. To assert influence in the region, China established an air-defence identification zone over the East China Sea in December. Aircraft flying into the zone are supposed to notify Chinese authorities beforehand.

Additionally, the Philippines and China are locked in a simmering conflict over claims to natural resources and a series of islands in the South China Sea. China has repeatedly tried to dislodge Philippine fishing vessels from the disputed waters.

In its stand-off with China, the Philippines needs the United States on its side.

"The Chinese see weakness here," Bower says. "The Chinese would take a failed agreement as a very real signal that the rebalance or pivot to Asia isn't taking root."

Obama, for his part, has promised to back the Philippines in its territorial disputes with China, however obliquely, and has made it clear that the island nation is key to the administration's Asia pivot. A planned Philippine naval base overlooking the disputed waters is even expected to berth US warships in the near future.

That's not to say that stronger military ties would deter China, or resolve its ongoing disputes with the Philippines. If the US and the Philippines manage to reach an agreement ahead of Obama's April visit, there's always a possibility that it will provoke China further.

"China is really determined to expand into the South China Sea," De Castro says. A bilateral military agreement could prove a temporary deterrent, he adds, but in the long run "the Chinese will do something to test the resolve and the commitment of the alliance".

Bower says that test could be the establishment of another Chinese air zone, this time in the South China Sea.

The Philippines' inability to respond to Haiyan, and the US readiness to do so, provided the missing rationale to the public for allowing US forces onto the island nation in greater numbers. Obama noted as much during his state-of-the-union address last week, saying: "Our Marines and civilians rushed to aid those battered by a typhoon, and were greeted with words like: 'We will never forget your kindness.'"