United States President George W Bush [Images], accompanied by First Lady Laura Bush, left for India and Pakistan, commencing his five-day trip. During this tour, he is expected to cement American alliances with the two South Asian countries and hammer out a landmark agreement to share civilian nuclear technology with New Delhi.

President Bush boarded Air Force One, the American presidential aircraft, Tuesday afternoon at around 1345 hours, (0015 IST) after a meeting at the White House with the Italian Prime Minister Silvio Berlusconi. He will reach New Delhi on Wednesday.

This is the President's first trip to the sub-continent. His delegation includes Secretary of State Condoleezza Rice [Images] and the new Assistant Secretary of State for South and Central Asia Richard Boucher.

Prominent American business leaders, including Ron Somers, president of the United States-India Business Council, are already in India ahead of Bush's arrival.

Both the President and Prime Minister Manmohan Singh [Images], in their recent interviews to the Indian and American media, have been talking about the multi-faceted bilateral relationship and the positive direction it is taking.

• The Indo-US nuclear tango

However, Bush's visit is primarily seen as revolving around the much-debated nuclear deal, which would entail civilian nuclear energy cooperation between India and the US.

Senior Bush administration officials like Stephen Hadley, the National Security Advisor, have been saying that if the deal is not inked during Bush's visit to India, the two sides will continue to iron it out.

However, all involved are optimistic that the deal will be hammered out while Bush is in India. One school of thought holds that Bush and Dr Singh, in their one-on-one meeting, can intervene and sort out whatever contentitious issues remain.

• 'There may not be a landmark agreement'

Bush will visit India with a major economic agenda, not just looking at ways of increasing American exports but also at avenues of investment, especially since the Indian economy has been doing well.

The President will be meeting Indian and American business leaders at a roundtable conference. There, he will probably hear the demand for increased visa numbers for skilled persons, notably in the H1B variety.

The visit will allow Bush to show India and Pakistan that the US values relations with each, despite complaints about closer ties in all three countries.

• PM wants US to rein in Pakistan

Pakistan is a key US ally, but many in Washington want to see Islamabad make stronger efforts to dismantle terrorist training camps.

The President is due to be back in Washington late on Saturday and it is quite possible that a quick trip to Afghanistan may also have been scheduled but not announced.

Complete coverage: President Bush in India