US Secretary of State Rex Tillerson, on his first visit to South Asia, is stepping into a tangled mass of relationships that has confounded diplomats for years. As he meets with the leaders of Afghanistan, India and Pakistan, Tillerson will focus on two of Washington's core foreign policy objectives on the Indian subcontinent.

First, the United States wants to find a way to wind down its involvement in the war in Afghanistan. The inexhaustible conflict — which pits a Taliban-led insurgency against the NATO-supported Afghan National Defense and Security Forces — continues to grind on after 16 years with no end in sight. Second, the United States is looking to build a defense-oriented partnership with India. That partnership is part of the wider US strategy to counterbalance China's increasingly assertive presence in the South China Sea in particular and in the Indo-Pacific in general. Although Washington has clear goals in South Asia, a variety of factors — the largest of which is Pakistan — will impede US progress.

Tillerson wants to build a more constructive working relationship with Pakistan to pursue US goals in the Afghan war. The United States works with Pakistan because of its leverage over the Taliban leadership, but Washington has long pressured Islamabad to pull its support for the militant group. For Washington, Islamabad might be the best way to pressure Taliban militants to stop fighting and start negotiating.

Pakistan, however, has resisted cooperation for strategic reasons. The Taliban offer Pakistan a way to ensure that post-conflict Afghanistan is friendly to Pakistani interests and hostile to India. That goal is fundamental to Pakistan's national security strategy, and it is the reason why the country will not be easily dissuaded from supporting the Taliban. After US President Donald Trump chastised the nuclear-armed state for refusing to abandon this strategy during a speech on Aug. 21, bilateral relations between the United States and Pakistan took a nosedive. Because of this, Tillerson's goal in Pakistan is to improve relations and enable future dialogue. But clashing US and Pakistani interests in Afghanistan mean that any harmony Tillerson creates will likely be fleeting. Cooperation, especially in Afghanistan, between the United States and India is sure to create dissonance in Pakistan.

Afghanistan factors into Tillerson's outreach to India as well. Trump has called for India to adopt a more active role in developing the landlocked country. India, for its part, has responded by announcing 116 development projects across all 31 Afghan provinces. The projects are part of the $3 billion in aid New Delhi has committed to Afghanistan to maintain its influence there since 2001. India also appears to be interested in a greater role in Afghan security. Indian national security adviser Ajit Doval visited Kabul on Oct. 16, the same day Pakistani officials were in Oman to participate in the revived Quadrilateral Coordination Group dialogue aimed at jump-starting Afghanistan negotiations. But Pakistani Prime Minister Shahid Khaqan Abbasi and other officials in Islamabad have already made it clear that Indian involvment in Afghanistan is a deal breaker. Because of this, Tillerson is unlikely to push for greater Indian involvement in Afghan security even though Afghanistan's president, Ashraf Ghani, arrived in New Delhi on Oct. 24 to bolster Afghan-Indian relations by meeting with Indian Prime Minister Narendra Modi.

In any case, Tillerson's goals for outreach to India extend far beyond the ruins of the Afghan war. On Oct. 18 in Washington, Tillerson gave a policy speech that highlighted the importance of US-India relations over the next 100 years in countering Chinese influence. Building a stronger defense partnership is a core part of those relations, as well as part of the wider US strategy to cultivate an informal trilateral alliance with India and Japan. But India's preference for maintaining strategic autonomy will constrain this aspect of the relationship.

Tillerson also highlighted the need to provide alternative sources of infrastructure financing for nations in the Indo-Pacific. The statement was a clear reference to China's massive Belt and Road Initiative, a pan-Eurasian project aimed at linking 64 countries through a network of roads, railways and pipelines. India has opted out of the initiative, choosing instead to push its own infrastructure projects such as the Chabahar port in Iran and the Trincomalee port in Sri Lanka. However, fiscal constraints and the languid pace of infrastructure projects mean progress will be constrained in this arena as well.

Military, security and strategic considerations are all key components of Tillerson's outreach in South Asia. But even as Washington's top diplomat tries to advance US goals in the region, the Gordian knot of Pakistani relations with India and Afghanistan will remain stubbornly entangled. As the United States and its allies push forward, those entanglements will make the road long, the process complex, and the outcome incomplete.

This essay was first published by Stratfor, the US-based global intelligence firm, with which Strategic Review has a content-sharing agreement.