In July, China's exposure stood at $1.22 trillion, followed by Japan, $1.15 trillion.
Latest data available with the US treasury department shows India raised its exposure by a little over $6 billion to $123.7 billion in July.
The same stood at $117.2 billion in June, slightly lower than $118.2 billion in the preceding month.
Before that, the country's holdings had touched a high of $121.6 billion in April while the exposure stood at $119.8 billion in January.
Among the BRIC (Brazil, Russia, India and China) nations, India has the third-highest holdings of US government securities after China and Brazil ($254.1 billion).
In July, Russia had trimmed its exposure to $88.2 billion.
Apart from China and Japan, other countries in the top ten are Ireland (3), Cayman Islands (4), Brazil (5), Switzerland (6), Luxembourg (7), the UK (8), Taiwan (9) and Hong Kong (10), according to the data.
At the 11th position is Belgium.
The US, which is the world's largest economy, is witnessing improved growth.
The country's real GDP rose to 1.4 per cent in the second quarter of this year, according to the third estimate released by the US Bureau of Economic Analysis last month.
As per the second estimate, the GDP grew 1.1 per cent in April-June period.
In the first three months of 2016, the economy had expanded 0.8 per cent.