By Jonathan Beale
BBC state department correspondent
In diplomacy, it is often hard to achieve tangible results, especially on a three-day visit.
The US sees India as an important democratic ally
Therefore, President Bush's South Asia tour will be viewed as a success. India and the US reached a landmark deal on civilian nuclear cooperation.
More than that, the agreement marked a new bond of trust.
After mutual Cold War suspicions, the US now sees India as an important ally - a partner to spread shared values of prosperity, democracy and freedom.
President Bush has still got to convince a sceptical US Congress that the nuclear deal is a good one.
Politicians on Capitol Hill question whether it will undermine international efforts to tackle the spread of nuclear weapons.
Remember, India has not signed the Nuclear Non-Proliferation Treaty, and its military programme will still be hidden away from international inspections.
The favouritism being shown to India is making other countries in the region wary
Some US politicians say that India is being rewarded for bad behaviour. Others fear the deal will send out entirely the wrong signal to Iran.
And President Bush's arguments so far have not been convincing.
He believes that helping India with its civilian nuclear programme will ease pressure on diminishing oil supplies. Well, not for a long time yet.
He also has to convince the international community that the US was right to bend the rules just for India.
The favouritism being shown to India is making other countries in the region wary.
Bush's South Asia tour sparked protests in three countries
Pakistan's President Musharraf has already asked for the same kind of help and been rebuffed. The US essentially says Pakistan cannot yet be trusted.
China - the major power in the region - will watch with some suspicion as to how the Indo-US relationship develops. Is India now a rival? How will Beijing now challenge America's influence?
Even though President Bush can look back on this visit with some satisfaction, he will also have been fully aware of the controversy he still creates.
In India, tens of thousands demonstrated ahead of his arrival. In Pakistan the police were swift to clamp down on protesters. His first visit to Afghanistan had to be carried out in secrecy.
President Bush may be a friend to those countries' leaders - but he is still hated by many of their people. American foreign policy is still defined by its war on terror. One swallow does not make a summer.