US President Donald Trump on Sunday expressed willingness to mediate a resolution to the decades-old Kashmir dispute between India and Pakistan, sarcastically terming it a conflict of "a thousand years," even as Pakistan breached a fresh ceasefire agreement within hours of its announcement.

New Delhi has been opposed to any third-party mediation on the issue as Kashmir is an integral part of India.

Posting on his social media platform, Truth Social, Trump lauded the ceasefire "understanding" between India and Pakistan that followed four days of escalating military hostilities triggered by the Pahalgam terror attack.

He warned that the situation could have led to the deaths of millions if not controlled in time.

"I am very proud of the strong and unwaveringly powerful leadership of India and Pakistan for having the strength, wisdom, and fortitude to fully know and understand that it was time to stop the current aggression that could have led to the death and destruction of so many, and so much. Millions of good and innocent people could have died! Your legacy is greatly enhanced by your brave actions," Trump wrote.

Claiming credit for the de-escalation, which Islamabad broke nearly two hours after Trump's announcement, he added, "I am proud that the USA was able to help you arrive at this historic and heroic decision. While not even discussed, I am going to increase trade, substantially, with both of these great Nations."

Trump also proposed to mediate the Kashmir issue, a highly sensitive subject between India and Pakistan.

"Additionally, I will work with you both to see if, after a 'thousand years', a solution can be arrived at concerning Kashmir. God Bless the leadership of India and Pakistan on a job well done!!!" he posted.

However, hours after the ceasefire agreement took effect on Saturday evening, Pakistani forces violated the understanding by launching drone attacks and shelling Indian territories.

Ceasefire violations were reported in Akhnoor, Mendhar, R.S. Pura, Chamb, Bhimber, and Gurez sectors. Loud explosions were also heard in Srinagar, despite the truce being scheduled to begin at 5 p.m.

Indian Foreign Secretary Vikram Misri, addressing a press conference on Saturday, confirmed that Indian forces have been responding "adequately" to the Pakistani breaches.

He noted that although the ceasefire understanding was reached to halt all military actions -- on land, in the air, and at sea -- Pakistan's actions have already compromised it.

"This is a breach of understanding. The army is monitoring the situation closely," Misri stated, emphasising that the Indian government has taken serious note of the fresh Pakistani provocations.

The ceasefire, though welcomed globally, now stands on shaky ground with the latest violations, raising questions over the feasibility of any long-term resolution -- especially on contentious issues like Kashmir, even with external mediation.