Trump has declined India's invitation to be the chief guest at the parade citing pressing engagements, including his State of The Union address, around the time India will celebrate its Republic Day on January 26.
Asked if Trump declining India's invitation had something to do with India signing a deal with Russia on S-400 missile defence systems, Juster, speaking to reporters on the sidelines of an event in New Delhi, said, "No, that is a purely scheduling issue."
Earlier this week, a White House spokesperson, when asked about Trump's decision, had said, "President Trump was honoured by Prime Minister Modi's invitation to him to be the chief guest of India's Republic Day on January 26, 2019, but is unable to participate due to scheduling constraints."
Prime Minister Narendra Modi had invited Trump for a visit to India during their talks in Washington in June, 2017.
Every year, India invites world leaders to attend its Republic Day celebrations.
In 2015, the then US president Barack Obama had attended it as the chief guest, which was his second visit to India as the American president.
On whether India will get a waiver from the US on Chabahar amid sanctions on Iran, Juster said, "These are matters that our two governments are discussing and we are working together on that."
India looks at alternatives after Trump turns down R-Day invite
'Trump likes Modi'
What Trump can learn from Modi
When Trump wanted to play matchmaker for PM Modi
Modi's road to Trump's heart