When President Obama greeted a news conference in Hyderabad House in New Delhi, India, on Sunday, he made an extra effort to use Hindi language and expressions. "Namaste. Mera Pyaar Bhara Namaskar," he said as he opened the news conference ("My greetings with affection"). "Chale saath saath," he said as it concluded ("lets walk together").

Obama's linguistic message was probably prompted by a desire to show humility and be a gracious guest. But in Narendra Modi's India, his choice of words fit into a changing world of diplomatic linguistics.

Last year, there were reports that the then-newly elected Prime Minister Modi would stick to speaking Hindi, rather than English, when meeting with foreign leaders. While other leaders have made similar decisions, the news prompted considerable debate in India about why Modi and the party he leads, Bharatiya Janata Party (BJP), would push Hindi when Modi can speak reasonably good English.

Hindi is an official language of the national government of India, though each Indian state chooses their own official language. According to the 2001 census, some 550 million Indians can speak Hindi, and more than 125 million can speak English. The country is very linguistically diverse, however, with 22 different languages considered official. In fact, Hindi is actually Modi's second language – he grew up speaking Gujarati.

In India, the English language is a sometimes controversial. A colonial import, it has become known as both the language of the country's secular elite but also those striving to succeed in a country now at the center of many international businesses. Modi, who has a humble background with roots in Hindu nationalism, may well balk at both. His government has also pushed the use of Sanskrit, an ancient Indian language considered the sacred language of Hinduism.

So far, Modi's use of Hindi on the international stage hasn't been absolute. While he gave a widely publicized speech in Hindi to the United Nations General Assembly, he has also addressed other world leaders in English. During Sunday's Hyderabad House news conference, he made a statement in English using a teleprompter, though he responded to questions from reporters in Hindi. He also had a number of casual conversations with Obama in English (and, incidentally, had his name written in Latin characters on his suit).

However, it's behind the scenes that the switch may be more noticeable. Devirupa Mitra recently wrote in the Sunday Express newspaper that India's Ministry of External Affairs has created a division devoted to promotion of the Hindi language. They had not only begun staffing up on interpreters but also increased the use of Hindi in internal communications.

Such slow yet steady moves are probably appropriate for the grand ambition of what appears to be Modi's linguistic mission: To make Hindi, by some estimates the fourth most prevalent language on Earth, an accepted global language.