India asserts sovereignty over Arunachal Pradesh, rejecting China's claim to the region.

• This month, as tensions rise between nuclear-armed India and China, the United States has issued a statement.

The U.S. has condemned China's "unilateral actions" to assert control over Arunachal Pradesh, taking a stance in the dispute between India and China following Prime Minister Narendra Modi's dedication of a tunnel in the northeastern Indian state.

The ongoing conflict between India and China, whose borders stretch over 3,500 kilometers, has reached a boiling point.

India asserts that Arunachal Pradesh has always been a part of India, while China claims it to be part of southern Tibet, referring to it as Zangnan.

On Wednesday, the U.S. State Department weighed in on the matter.

The Line of Actual Control (LAC) marks the boundary between India and China's territorial control.

Michael Kugelman, director of the South Asia Institute at the Wilson Center, stated that the statement reflects consistent U.S. efforts to align itself with India in its competition with China, as he told CNBC.

Kugelman noted that the U.S. usually avoids commenting on certain Indian border disputes, such as the one with Pakistan over Kashmir. However, in this instance, Washington is demonstrating its support for New Delhi by taking similar actions, including intelligence-sharing, to help India prevent Chinese aggressions on its northern border.

This month, India's Prime Minister Narendra Modi unveiled the "Sela Tunnel," a bi-lane tunnel constructed at over 13,000 feet, sparking criticism from Chinese officials.

The conflict between India and China has intensified, culminating in a deadly clash in 2020 that resulted in the deaths of 20 Indian soldiers and four Chinese troops. Additionally, China's decision to rename 11 places in Arunachal Pradesh was met with strong opposition from India.

Senior Colonel Zhang Xiaogang, deputy director general of the Information Office of China's Ministry of National Defense stated that "China does not acknowledge and strongly condemns India's unlawful formation of the so-called 'Arunachal Pradesh' following the road tunnel's opening."

The defense ministry of China restated its assertion over the northeastern state of Arunachal Pradesh last week.

The Indian foreign ministry rebutted Zhang's remarks by asserting that Arunachal Pradesh will forever remain a part of India.

The Indian foreign ministry spokesperson, Randhir Jaiswal, stated in an official statement that the Chinese Defense Ministry made "unfounded assertions" about the Indian state of Arunachal Pradesh and "repeating baseless arguments does not add any credibility to such claims."

Harsh V. Pant, vice president for studies and foreign policy at Observer Research Foundation, stated that the U.S. standing up for India demonstrates the progress of India-U.S. relations.

The U.S. is openly supporting India in the sensitive matter of the India-China border dispute, as stated by him to CNBC.

— CNBC's Naman Tandon contributed to this story.